This is geiser.info, produced by makeinfo version 6.7 from geiser.texi.
This manual documents Geiser, an Emacs environment to hack in Scheme.
Copyright (C) 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2018, 2020,
2021 Jose Antonio Ortega Ruiz
Permission is granted to copy, distribute and/or modify this
document under the terms of the GNU Free Documentation License,
Version 1.3 or any later version published by the Free Software
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INFO-DIR-SECTION Emacs
START-INFO-DIR-ENTRY
* Geiser: (geiser). Emacs environment for Scheme hacking.
END-INFO-DIR-ENTRY
File: geiser.info, Node: Top, Next: Introduction, Prev: (dir), Up: (dir)
Geiser
******
* Menu:
* Introduction::
* Installation::
* The REPL::
* Between the parens::
* Cheat sheet::
* No hacker is an island::
* Index::
-- The Detailed Node Listing --
Introduction
* Modus operandi::
* Showing off::
Installation
* Must needs::
* The quick and easy way::
* From the source's mouth::
* Friends::
The REPL
* Starting the REPL::
* First aids::
* Switching context::
* Completion and error handling::
* Autodoc and friends::
* Seeing is believing::
* Customization and tips::
Between the parens
* Activating Geiser::
* The source and the REPL::
* Documentation helpers::
* To eval or not to eval::
* To err perchance to debug::
* Jumping around::
* Geiser writes for you::
Cheat sheet
* Scheme buffers::
* REPL::
* Documentation browser::
Geiser is a collection of Emacs major and minor modes that conspire with
one or more Scheme interpreters to keep the Lisp Machine Spirit alive.
It draws inspiration (and a bit more) from environments such as Common
Lisp's Slime, Factor's FUEL, Squeak or Emacs itself, and does its best
to make Scheme hacking inside Emacs (even more) fun.
Or, to be precise, what i (https://jao.io) consider fun. Geiser is
thus my humble contribution to the dynamic school of expression, and a
reaction against what i perceive as a derailment, in modern times, of
standard Scheme towards the static camp. Because i prefer growing and
healing to poking at corpses, the continuously running Scheme
interpreter takes the center of the stage in Geiser. A bundle of Elisp
shims orchestrates the dialog between the Scheme interpreter, Emacs and,
ultimately, the schemer, giving her access to live metadata. Here's
how.
File: geiser.info, Node: Introduction, Next: Installation, Prev: Top, Up: Top
1 Introduction
**************
Geiser is an Emacs environment to hack and have fun in Scheme. If
that's enough for you, see *note Installation:: to get it running and
*note The REPL:: for the fun part.
* Menu:
* Modus operandi::
* Showing off::
File: geiser.info, Node: Modus operandi, Next: Showing off, Prev: Introduction, Up: Introduction
1.1 Modus operandi
==================
As already mentioned, Geiser relies on a running Scheme process to
obtain the information it makes accessible to the programmer. There's
little effort, on the Elisp side, to understand, say, the module system
used by the Scheme implementation at hand; instead, a generic interface
between the two worlds is defined, and each supported Scheme includes a
library implementing that API, together with some wee shims in Elisp
allowing the reuse of the Emacs-side framework, which constitutes the
bulk of the code.
While being as generic as possible, the Scheme-Elisp interface makes
some assumptions about the capabilities and interaction mode of the
corresponding REPL. In particular, Geiser expects the latter to support
namespaces in the form of a module system, and to provide a well-defined
way to establish the REPL's current namespace (or module), as well as
the current file's module (or namespace). Thus, all evaluations
performed by Geiser either in the REPL or in a source code buffer happen
in the context of the current namespace. Every time you switch to a
different file, you're switching namespaces automatically; at the REPL,
you must request the switch explicitly (usually just using means
provided by the Scheme implementation itself).
If your favourite Scheme supports the above modus operandi, it has
all that's needed for a bare-bones Geiser mode. But Geiser can, and
will, use any metadata available: procedure arities and argument lists
to display interactive help, documentation strings, location information
to jump to definitions, export lists to provide completion, and so on
and so forth. Although this is not an all-or-none proposition (Geiser
can operate with just part of that functionality available), i initially
concentrated in supporting those Schemes with the richest (to my
knowledge) introspection capabilities, namely, Guile and Racket. Later
on, Dan Leslie added support for Chicken, and several other schemes
followed suit.
File: geiser.info, Node: Showing off, Prev: Modus operandi, Up: Introduction
1.2 Showing off
===============
When working with a fully conniving Scheme, Geiser can offer the
following functionality:
* Form evaluation in the context of the current file's module.
* Macro expansion.
* File/module loading and/or compilation.
* Namespace-aware identifier completion (including local bindings,
names visible in the current module, and module names).
* Autodoc: the echo area shows information about the signature of the
procedure/macro around point automatically.
* Jump to definition of identifier at point.
* Access to documentation (including docstrings when the
implementation provides it).
* Listings of identifiers exported by a given module.
* Listings of callers/callees of procedures.
* Rudimentary support for debugging (when the REPL provides a
debugger) and error navigation.
* Support for multiple, simultaneous REPLs.
* Support for image display in those Schemes that treat them as first
class values.
In the following pages, i'll try to explain what these features
actually are (i'm just swanking here), and how to use them for your
profit. But, before that, let's see how to install Geiser.
File: geiser.info, Node: Installation, Next: The REPL, Prev: Introduction, Up: Top
2 Installation
**************
* Menu:
* Must needs::
* The quick and easy way::
* From the source's mouth::
* Friends::
File: geiser.info, Node: Must needs, Next: The quick and easy way, Prev: Installation, Up: Installation
2.1 Must needs
==============
If Geiser came with any guarantees, you'd break all of them by not using
GNU Emacs 24.4 (or better: i regularly use it with a recent Emacs
snapshot) and at least one of the supported Schemes, namely:
* Chez (9.4) 9.4 or better, via geiser-chez
(https://gitlab.com/emacs-geiser/chez)
* Chibi (0.7.3) 0.7.3 or better, via geiser-chibi
(https://gitlab.com/emacs-geiser/chibi)
* Chicken (4.8.0) 4.8.0 or better, via geiser-chicken
(https://gitlab.com/emacs-geiser/chicken)
* Gambit (4.9.3) 4.9.3 or better, via geiser-gambit
(https://gitlab.com/emacs-geiser/gambit)
* Gauche (0.9.6) 0.9.6 or better, via geiser-gauche
(https://gitlab.com/emacs-geiser/gauche)
* Guile (2.2) 2.2 or better, via geiser-guile
(https://gitlab.com/emacs-geiser/guile)
* GNU Kawa (3.1) 3.1 or better, via geiser-kawa
(https://gitlab.com/emacs-geiser/kawa)
* MIT/GNU Scheme (9.0) 9.0 or better, via geiser-mit
(https://gitlab.com/emacs-geiser/mit)
* Racket (7.0) 7.0 or better, via geiser-racket
(https://gitlab.com/emacs-geiser/racket)
* Stklos (1.50) 1.50 or better, via geiser-stklos
(https://gitlab.com/emacs-geiser/stklos)
Since Geiser supports multiple REPLs, having all of them will just
add to the fun.
You'll also need Geiser itself. The quickest installation is via
your favourite implementation's ELPA packages (as of this writing,
they're all available in MELPA and (most of them) also in NonGNU ELPA,
which comes included with the batteries of Emacs 28 or better).
File: geiser.info, Node: The quick and easy way, Next: From the source's mouth, Prev: Must needs, Up: Installation
2.2 The quick and easy way
==========================
Did i mention that the easiest way of installing Geiser is using its
ELPA (http://emacswiki.org/emacs/ELPA) package? If you're using Emacs
24, ELPA (http://emacswiki.org/emacs/ELPA) is already there; for earlier
versions, the page i just linked to twice will tell you where to find
the goodies.
ELPA packages live in repositories accessible via HTTP. You can find
Geiser's package in either NonGNU ELPA
(https://elpa.nongnu.org/nongnu/geiser.html) or, if you like living on
the bleeding edge, MELPA (http://melpa.org/#/geiser) (directly from the
git repo). To tell Emacs that an ELPA repo exists, you add it to
'package-archives'(1):
(require 'package)
(add-to-list 'package-archives
'("nongnu" . "https://elpa.nongnu.org/nongnu/"))
(package-initialize)
And then installing your favourite Geiser is as easy as (if, say,
you're a MIT aficionado):
M-x package-install RET geiser-mit RET
Rinse and repeat for each of the scheme implementations that you
would like to use. Some of them (e.g. Gambit or Chicken) have a bit of
additional setup, specific to them, so make sure you also check their
respective package documentation.
With that, you are pretty much all set up. See *note The REPL:: to
start using Geiser.
---------- Footnotes ----------
(1) If you're using Emacs 28 or better, 'package-archives' already
comes with the non-gnu archive preconfigured, so you're lucky in more
than one way.
File: geiser.info, Node: From the source's mouth, Next: Friends, Prev: The quick and easy way, Up: Installation
2.3 Installing from source
==========================
All Geiser packages are ready to be used out of the box without much
more ado. For the sake of concreteness, let's assume you put its source
in the directory '~/lisp/geiser'. All you need to do is to add the
following line to your Emacs initialisation file (be it '~/.emacs',
'~/.emacs.d/init.el' or any of its moral equivalents):
(add-to-list 'load-path "~/lisp/geiser/elisp")
and, if your, say, 'geiser-gambit' checkout lives in
'~/lisp/geiser-mit' add to that:
(add-to-list 'load-path "~/lisp/geiser-gambit")
The autoloads defined in those packages should be enough to start
scheming.
File: geiser.info, Node: Friends, Prev: From the source's mouth, Up: Installation
2.4 Friends
===========
Although Geiser does not need them, it plays well with (and is enhanced
by) the following Emacs packages:
* Paredit (http://www.emacswiki.org/emacs/ParEdit). Regardless of
whether you use Geiser or not, you shouldn't be coding in any Lisp
dialect without the aid of Taylor Campbell's structured editing
mode.
* Company (http://company-mode.github.io/). Nikolaj Schumacher's and
Dmitry Gutov's 'company-mode' provides a generic front-end for
completion engines (such as Geiser's), with pretty and automatic
completion lists.
* macrostep-geiser (https://github.com/nbfalcon/macrostep-geiser)
provides support for in-buffer macro expansion, using the macrostep
(https://github.com/joddie/macrostep) package.
* ac-geiser (https://github.com/xiaohanyu/ac-geiser/) If you prefer
'auto-complete-mode' to 'company-mode', Xiao Hanyu's 'ac-geiser',
which provides a Geiser plugin for the popular Emacs Auto
Completion Mode (https://www.emacswiki.org/emacs/AutoComplete), is
the package for you. Like Geiser, 'ac-geiser' is available in
MELPA, and also as an 'el-get' package.
You just need to install and setup them as usual, for every package's
definition of usual. Geiser will notice their presence and react
accordingly.
File: geiser.info, Node: The REPL, Next: Between the parens, Prev: Installation, Up: Top
3 The REPL
**********
If you've followed the instructions in *note Installation::, your Emacs
is now ready to start playing. Otherwise, i'll wait for you: when
you're ready, just come back here and proceed to the following sections.
* Menu:
* Starting the REPL::
* First aids::
* Switching context::
* Completion and error handling::
* Autodoc and friends::
* Seeing is believing::
* Customization and tips::
File: geiser.info, Node: Starting the REPL, Next: First aids, Prev: The REPL, Up: The REPL
3.1 Starting the REPL
=====================
To start a Scheme REPL (meaning, a Scheme process offering you a
Read-Eval-Print Loop), Geiser provides the generic interactive command
'geiser'. If you invoke it (via, as is customary in Emacs, 'M-x
geiser'), you'll be saluted by a prompt asking which one of the
supported implementations you want to launch--yes, you can stop the
asking, see *note below: active-implementations. Tabbing for completion
will offer you, as of this writing, 'guile', 'racket', 'chicken', 'mit',
'chibi' and 'chez'. Just choose your poison, and a new REPL buffer will
pop up (by default, the REPL will appear in a new window: if that annoys
you, just set 'geiser-repl-use-other-window' to 'nil' and the current
window will be used).
If all went according to plan, you'll be facing an
implementation-dependent banner, followed by an interactive prompt.
Going according to plan includes having the executable of the Scheme you
chose in your path. If that's not the case, you can tell Emacs where it
is, as described in *note a moment: impl-binary. Returning to our REPL,
the first thing to notice is that the funny prompt is telling you your
current module: its name is the part just after the @ sign (in Guile,
that means 'guile-user', while Racket's and Chicken's top namespaces
don't have a name; cf. discussion in *note Switching context::). Other
than that, this is pretty much equivalent to having a command-line
interpreter in a terminal, with a bunch of add-ons that we'll be
reviewing below. You can start typing sexps right there: Geiser will
only dispatch them for evaluation when they're complete, and will indent
new lines properly until then. It will also keep track of your input,
maintaining a history file that will be reloaded whenever you restart
the REPL.
If you're not happy with the faces Geiser is using for the REPL's
prompt and evaluated input, you can customise
'geiser-font-lock-repl-prompt' and 'geiser-font-lock-repl-input' to
better-looking faces.
Connecting to an external Scheme
................................
There's an alternative way of starting a Geiser REPL: you can connect to
an external Scheme process, provided it's running a REPL server at some
known port. How to make that happen depends on the Scheme
implementation.
If you use Guile, you just need to start your Guile process (possibly
outside Emacs) passing to it the flag '--listen'. This flag accepts an
optional port as argument (as in '--listen=1969'), if you don't want to
use the default.
In Racket, you have to use the REPL server that comes with Geiser.
To that end, put Geiser's Racket 'scheme' directory in Racket's
collection search path and invoke 'start-geiser' (a procedure in the
module 'geiser/server') somewhere in your program, passing it the
desired port and, if desired, network interface name. This procedure
will start the REPL server in a separate thread. For an example of how
to do that, see the script 'bin/geiser-racket.sh' in the source
distribution, or, if you've compiled Geiser, 'bin/geiser-racket-noinst'
in the build directory, or, if you've installed Geiser, 'geiser-racket'
in '<installation-prefix>/bin'. These scripts start a new interactive
Racket that is also running a REPL server (they also load the errortrace
library to provide better diagnostics, but that's not strictly needed).
With your external Scheme process running and serving, come back to
Emacs and execute 'M-x geiser-connect', 'M-x connect-to-guile' or 'M-x
connect-to-racket'. You'll be asked for a host and a port, and, voila,
you'll have a Geiser REPL that is served by the remote Scheme process in
a dedicated thread, meaning that your external program can go on doing
whatever it was doing while you tinker with it from Emacs. Note,
however, that all Scheme threads share the heap, so that you'll be able
to interact with those other threads in the running Scheme from Emacs in
a variety of ways. For starters, all your (re)definitions will be
visible everywhere. That's dangerous, but will come in handy when you
need to debug your running web server.
The connection between Emacs and the Scheme process goes over TCP, so
it can be as remote as you need, perhaps with the intervention of an SSH
tunnel.
File: geiser.info, Node: First aids, Next: Switching context, Prev: Starting the REPL, Up: The REPL
3.2 First aids
==============
A quick way of seeing what else Geiser's REPL can do for you, is to
display the corresponding entry up there in your menu bar. No, i don't
normally use menus either; but they can come in handy until you've
memorized Geiser's commands, as a learning device. And yes, i usually
run Emacs inside a terminal, but one can always use La Carte
(http://www.emacswiki.org/emacs/LaCarte) to access the menus in a
convenient enough fashion.
Or just press 'C-h m' and be done with that.
Among the commands at your disposal, we find the familiar input
navigation keys, with a couple twists. By default, 'M-p' and 'M-n' are
bound to matching items in your input history. That is, they'll find
the previous or next sexp that starts with the current input prefix
(defined as the text between the end of the prompt and your current
position, a.k.a. "point", in the buffer). For going up and down the
list unconditionally, just use 'C-c M-p' and 'C-c M-n'. In addition,
navigation is sexp-based rather than line-based.
There are also a few commands to twiddle with the Scheme process.
'C-c C-q' will gently ask it to quit, while 'C-u C-c C-q' will
mercilessly kill the process (but not before stowing your history in the
file system). Unless you're using a remote REPL, that is, in which case
both commands will just sever the connection and leave the remote
process alone. If worse comes to worst and the process is dead, 'C-c
C-z' will restart it. However, the same shortcut, issued when the REPL
is alive, will bring you back to the buffer you came from, as explained
in *note this section: switching-repl-buff.
The remaining commands are meatier, and deserve sections of their
own.
File: geiser.info, Node: Switching context, Next: Completion and error handling, Prev: First aids, Up: The REPL
3.3 Switching context
=====================
In tune with Geiser's modus operandi, evaluations in the REPL take place
in the namespace of the current module. As noted above, the REPL's
prompt tells you the name of the current module. To switch to a
different one, you can use the command 'geiser-repl-switch-to-module',
bound to 'C-c C-m'. You'll notice that Geiser simply uses a couple of
meta-commands provided by the Scheme REPL (the stock ',m' in Guile and
Chicken and the (geiser-defined) ',enter' in Racket), and that it
doesn't even try to hide that fact. That means that you can freely use
said native ways directly at the REPL, and Geiser will be happy to
oblige. In Racket, ',enter' works like Racket's standard 'enter!' form,
but you can also provide a path string as its argument (e.g., ',enter
"/tmp/foo.rkt"' is equivalent to ',enter (file "/tmp/foo.rkt")'). Like
'enter!', ',enter' accepts also module names (as in, say, ',enter
geiser/main'). As mentioned, in Guile and Chicken, ',m' is used as is.
Once you enter a new module, only those bindings visible in its
namespace will be available to your evaluations. All Schemes supported
by Geiser provide a way to import new modules in the current namespace.
Again, there's a Geiser command, 'geiser-repl-import-module', to invoke
such functionality, bound this time to 'C-c C-i'. And, again, you'll
see Geiser just introducing the native incantation for you, and you're
free to use such incantations by hand whenever you want.
One convenience provided by these two Geiser commands is that
completion is available when introducing the new module name, using the
'<TAB>' key. Pressing it at the command's prompt will offer you a
prefix-aware list of available module names.
Which brings me to the next group of REPL commands.
File: geiser.info, Node: Completion and error handling, Next: Autodoc and friends, Prev: Switching context, Up: The REPL
3.4 Completion and error handling
=================================
We've already seen Geiser completion of module names in action at the
minibuffer. You won't be surprised to know that it's also available at
the REPL buffer itself. There, you can use either 'C-.' or 'M-`' to
complete module names, and '<TAB>' or 'M-<TAB>' to complete identifiers.
Geiser will know what identifiers are bound in the current module and
show you a list of those starting with the prefix at point. Needless to
say, this is not a static list, and it will grow as you define or import
new bindings in the namespace at hand. If no completion is found,
'<TAB>' will try to complete the prefix after point as a module name.
REPL buffers use Emacs' compilation mode to highlight errors reported
by the Scheme interpreter, and you can use the 'next-error' command
('M-g n') to jump to their location. By default, every time you enter a
new expression for evaluation old error messages are forgotten, so that
'M-g n' will always jump to errors related to the last evaluation
request, if any. If you prefer a not-so-forgetful REPL, set the
customization variable 'geiser-repl-forget-old-errors-p' to 'nil'.
Note, however, that even when that variable is left as 't', you can
always jump to an old error by moving to its line at the REPL and
pressing '<RET>'. When your cursor is away from the last prompt,
'<TAB>' will move to the next error in the buffer, and you can use
'<BACKTAB>' everywhere to go to the previous one.
Caveat about completion & the REPL
----------------------------------
It is possible for Geiser to hang your Emacs process when trying to
complete symbols. This can happen in the REPL itself or even in a
Scheme buffer that is attached to the REPL process. If this happens,
you've probably entered a module that changes the REPL prompt from what
Geiser was expecting to see.
Unfortunately, there's no general solution for this issue right now
(as it is a daunting task to try to make a regexp that can encompass all
possible REPL prompts). The best solution for now is to fix this issue
on a case-by-case basis by adjusting your prompt regexp variable so that
it matches the default prompt as well as your Scheme module's special
prompt.
For example, XREPL is a Racket module that implements a better Racket
REPL. You might be interested in toying around with some of its
functions, but when you try to enter XREPL via, say, 'C-c C-m xrepl',
you'll notice that the REPL prompt has changed to something like this:
<pkgs>/xrepl-lib/xrepl/main>
If you start typing symbols, and then you try to auto-complete those
symbols, your Emacs process may hang. This is because Geiser expects
the REPL prompt to match this regexp (for Racket):
"\\(mzscheme\\|racket\\)@[^ ]*> "
Therefore, we can fix this issue by changing our default prompt
regexp like so:
(setq geiser-racket--prompt-regexp "<pkgs>.*> \\|\\(mzscheme\\|racket\\)@[^ ]*> ")
Note that you may have to run 'M-x geiser-reload' after setting this
variable so that your changes will take effect.
Again, you'll have to change the regexp to fit every prompt that
causes this issue, but the only alternative (that we can think of right
now) is to create a regexp that will match every possible prompt.
Obviously, that is going to be more than a little tricky. However, if
you have a better solution than that, please share it with the Geiser
developers; we'll be more than happy to hear it.
File: geiser.info, Node: Autodoc and friends, Next: Seeing is believing, Prev: Completion and error handling, Up: The REPL
3.5 Autodoc and friends
=======================
Oftentimes, there's more you'll want to know about an identifier besides
its name: What module does it belong to? Is it a procedure and, if so,
what arguments does it take? Geiser tries to help you answering those
questions too.
Actually, if you've been playing with the REPL as you read, you might
have notice some frantic activity taking place in the echo area every
now and then. That was Geiser trying to be helpful (while, hopefully,
not being clippy), or, more concretely, what i call, for want of a
better name, its "autodoc" mode. Whenever it's active (did you notice
that A in the mode-line?), Geiser's gerbils will be scanning what you
type and showing (unless you silence them with 'C-c C-d C-a')
information about the identifier nearest to point.
If that identifier corresponds to a variable visible in the current
namespace, you'll see the module it belongs to and its value. For
procedures and macros, autodoc will display, instead of their value, the
argument names (or an underscore if Geiser cannot determine the name
used in the definition). Optional arguments are surrounded by
parentheses. When the optional argument has a default value, it's
represented by a list made up of its name and that value. When the
argument is a keyword argument, its name has "#:" as a prefix.
If that's not enough documentation for you, 'C-c C-d d' will open a
separate documentation buffer with help on the symbol at point. This
buffer will contain implementation-specific information about the
identifier (e.g., its docstring for Guile, or its contract, if any, for
Racket), and a handy button to open the corresponding manual entry for
the symbol, which will open an HTML page (for Racket and Chicken) or the
texinfo manual (for Guile). If you'd rather go directly to the manual,
try 'C-c C-d i', which invokes 'geiser-doc-look-up-manual' as the handy
button does.
Geiser can also produce for you a list, classified by kind, of the
identifiers exported by a given module: all you need to do is press 'C-c
C-d m', and type or complete the desired module's name.
The list of exported bindings is shown, again, in a buffer belonging
to Geiser's documentation browser, where you have at your disposal a
bunch of navigation commands listed in *note our cheat-sheet:
Documentation browser.
We'll have a bit more to say about the documentation browser in *note
a later section: doc-browser.
If that's still not enough, Geiser can jump, via 'M-.', to the
symbol's definition. A buffer with the corresponding file will pop up,
with its point resting upon the identifier's defining form. When you're
done inspecting, 'M-,' will bring you back to where you were. As we
will see, these commands are also available in Scheme buffers. 'M-.'
also works for modules: if your point is on an unambiguous module name,
the file where it's defined will be opened for you.
File: geiser.info, Node: Seeing is believing, Next: Customization and tips, Prev: Autodoc and friends, Up: The REPL
3.6 Seeing is believing
=======================
In schemes that support images as values (currently, that means Racket),
the REPL will display them inline if you're using them in a
graphics-aware Emacs.
For the terminal, images will appear as buttons: press return on them
to invoke an external viewer (configurable via 'geiser-image-viewer')
that will show you the image at hand. You can also ask for the same
behaviour on all emacsen by customising 'geiser-repl-inline-images-p' to
'nil'.
Geiser keeps a cache of the last displayed images in the directory
'geiser-image-cache-dir', which defaults to the system's temp directory,
with up to 'geiser-image-cache-keep-last' files. You can invoke the
external image viewer on any of them with 'M-x geiser-view-last-image',
which takes a prefix argument to indicate which image number you want, 0
corresponding to the newest one.
File: geiser.info, Node: Customization and tips, Prev: Seeing is believing, Up: The REPL
3.7 Customization and tips
==========================
The looks and ways of the REPL can be fine-tuned via a bunch of
customization variables. You can see and modify them all in the
corresponding customization group (by using the menu entry or the good
old 'M-x customize-group geiser-repl'), or by setting them in your Emacs
initialisation files (as a rule, all knobs in Geiser are tunable this
way: you don't need to use customization buffers if you don't like
them).
I'm documenting below a proper subset of those settings, together
with some related tips.
Choosing a Scheme implementation
................................
Instead of using the generic 'geiser' command, you can directly start
your Scheme of choice using any of the following commands:
* 'run-racket'
* 'run-guile'
* 'run-chicken'
* 'run-mit'
* 'run-chibi'
* 'run-chez'
In addition, the variable 'geiser-active-implementations' contains a
list of those Schemes Geiser should be aware of. Thus, if you happen to
be, say, a racketeer not to be beguiled by other schemes, you can tell
Geiser to forget about the richness of the Scheme ecosystem with
something like:
(setq geiser-active-implementations '(racket))
in your initialisation files.
When starting a new REPL, Geiser assumes, by default, that the
corresponding Scheme binary is in your path. If that's not the case,
the variables to tweak are (depending on which Scheme you choose):
* 'geiser-guile-binary'
* 'geiser-racket-binary'
* 'geiser-chicken-binary'
* 'geiser-mit-binary'
* 'geiser-chibi-binary'
* 'geiser-chez-binary'
They should be set to a string with the full path to the requisite
binary.
Before starting the REPL, Geiser will check whether the version of
your Scheme interpreter is good enough. This means that it will spend a
couple tenths of a second launching and quickly discarding a Scheme
process, but also that the error message you'll get if you're on the
wrong Scheme version will be much more informative. If you one to avoid
version checks, just check 'geiser-repl-skip-version-check-p' to 't' in
your configuration.
Init files and load paths
.........................
The startup behaviour of the REPL can be also fine tuned with a couple
more initialisation parameters.
Many Scheme implementations provide a configuration variable to
specify a Geiser-specific init file (e.g., 'geiser-guile-init-file' for
Guile), and, sometimes a global list of paths to add to the
interpreter's load path (that'd be 'geiser-guile-load-path' for Guile).
There is also a generic mechanism to specify how to add directories
to the initial load path when 'geiser-repl-current-project-function' is
set: you can then customize 'geiser-repl-add-project-paths' to a list of
subdirectories of the project's root to add to the load path. When this
option is set, the working directory of the REPL's buffer (i.e., the
value of the elisp variable 'default-directory') will be set to the
directory returned by 'geiser-repl-current-project-function').
These variables controlling your scheme's initialisation process are
good candidates for an entry in a project's '.dir-locals.el' file, so
that they are automatically set to a sensible value whenever you start a
REPL in the project's directory.
Startup waiting time
....................
When starting a scheme implementation in old or very busy computers,
Geiser might have to wait a bit more than it expects (which is ten
seconds, or ten thousand milliseconds, by default). If you find that
Geiser is giving up too quickly and complaining that no prompt was
found, try to increase the value of 'geiser-repl-startup-time' to, say,
twenty seconds:
(setq geiser-repl-startup-time 20000)
If you prefer, you can use the customize interface to, well, customise
the above variable's value.
History
.......
By default, Geiser won't record duplicates in your input history. If
you prefer it did, just set 'geiser-repl-history-no-dups-p' to 'nil'.
History entries are persistent across REPL sessions: they're saved in
implementation-specific files whose location is controlled by the
variable 'geiser-repl-history-filename'. For example, my Geiser
configuration includes the following line:
(setq geiser-repl-history-filename "~/.emacs.d/geiser-history")
which makes the files 'geiser-history.guile' and 'geiser-history.racket'
to live inside my home's '.emacs.d' directory.
Autodoc
.......
If you happen to love peace and quiet and prefer to keep your REPL's
echo area free from autodoc's noise, 'geiser-repl-autodoc-p' is the
customization variable for you: set it to 'nil' and autodoc will be
disabled by default in new REPLs. You can always bring the fairies
back, on a per-REPL basis, using 'C-c C-d C-a'.
Remote connections
..................
When using any of the connection commands (e.g. 'geiser-connect',
'connect-to-guile', 'connect-to-racket', etc.) you'll be prompted for a
host and a port, defaulting to "localhost" and 37146. You can change
those defaults customizing 'geiser-repl-default-host' and
'geiser-repl-default-port', respectively.
Killing REPLs
.............
If you don't want Emacs to ask for confirmation when you're about to
kill a live REPL buffer (as will happen, for instance, if you're exiting
Emacs before closing all your REPLs), you can set the flag
'geiser-repl-query-on-kill-p' to 'nil'. On a related note, the
customizable variable 'geiser-repl-query-on-exit-p' controls whether
Geiser should ask for confirmation when you exit the REPL explicitly
(via, say, 'C-c C-q', as opposed to killing the buffer), and is set to
'nil' by default.
File: geiser.info, Node: Between the parens, Next: Cheat sheet, Prev: The REPL, Up: Top
4 Between the parens
********************
A good REPL is a must, but just about half the story of a good Scheme
hacking environment. Well, perhaps a bit more than a half; but, at any
rate, one surely needs also a pleasant way of editing source code.
Don't pay attention to naysayers: Emacs comes with an excellent editor
included for about any language on Earth, and just the best one when
that language is sexpy (especially if you use Paredit). Geiser's
support for writing Scheme code adds to Emacs' 'scheme-mode', rather
than supplanting it; and it does so by means of a minor mode
(unimaginatively dubbed 'geiser-mode') that defines a bunch of new
commands to try and, with the help of the same Scheme process giving you
the REPL, make those Scheme buffers come to life.
* Menu:
* Activating Geiser::
* The source and the REPL::
* Documentation helpers::
* To eval or not to eval::
* To err perchance to debug::
* Jumping around::
* Geiser writes for you::
File: geiser.info, Node: Activating Geiser, Next: The source and the REPL, Prev: Between the parens, Up: Between the parens
4.1 Activating Geiser
=====================
With Geiser installed following any of the procedures described in *note
The quick and easy way:: or *note From the source's mouth::, Emacs will
automatically activate geiser-mode when opening a Scheme buffer. Geiser
also instructs Emacs to consider files with the extension 'rkt' part of
the family, so that, in principle, there's nothing you need to do to
ensure that Geiser's extensions will be available, out of the box, when
you start editing Scheme code.
Indications that everything is working according to plan include the
'Geiser' minor mode indicator in your mode-line and the appearance of a
new entry for Geiser in the menu bar. If, moreover, the mode-line
indicator is the name of a Scheme implementation, you're indeed in a
perfect world; otherwise, don't despair and keep on reading: i'll tell
you how to fix that in a moment.
The menu provides a good synopsis of everything Geiser brings to the
party, including those keyboard shortcuts we Emacsers love. If you're
seeing the name of your favourite Scheme implementation in the
mode-line, have a running REPL and are comfortable with Emacs, you can
stop reading now and, instead, discover Geiser's joys by yourself. I've
tried to make Geiser as self-documenting as any self-respecting Emacs
package should be. If you follow this route, make sure to take a look
at Geiser's customization buffers ('M-x customize-group <RET> geiser'):
there's lot of fine-tuning available there. You might also want to take
a glance at the tables in *note our cheat sheet: Cheat sheet.
Since geiser-mode is a minor mode, you can toggle it with 'M-x
geiser-mode', and control its activation in hooks with the functions
'turn-on-geiser-mode' and 'turn-off-geiser-mode'. If, for some reason i
cannot fathom, you prefer geiser-mode not to be active by default,
customizing 'geiser-mode-auto-p' to 'nil' will do the trick.
And if you happen to use a funky extension for your Scheme files that
is not recognised as such by Emacs, just tell her about it with:
(add-to-list 'auto-mode-alist '("\\.funky-extension\\'" . scheme-mode))
Now, geiser-mode is just a useless wretch unless there's a running
Scheme process backing it up. Meaning that virtually all the commands
it provides require a REPL up and running, preferably corresponding to
the correct Scheme implementation. In the following section, we'll see
how to make sure that that's actually the case.
File: geiser.info, Node: The source and the REPL, Next: Documentation helpers, Prev: Activating Geiser, Up: Between the parens
4.2 The source and the REPL
===========================
As i've already mentioned a couple of times, geiser-mode needs a running
REPL to be operative. Thus, a common usage pattern will be for you to
first call 'geiser' (or one of its variants, e.g. 'run-guile'), and
then open some Scheme files; but there's nothing wrong in first opening
a couple Scheme buffers and then starting the REPL (you can even find it
more convenient, since pressing 'C-c C-z' in a Scheme buffer will start
the REPL for you). Since Geiser supports more than one Scheme
implementation, though, there's the problem of knowing which of them is
to be associated with each Scheme source file. Serviceable as it is,
geiser-mode will try to guess the correct implementation for you,
according to the algorithm described below.
How Geiser associates a REPL to your Scheme buffer
..................................................
To determine what Scheme implementation corresponds to a given source
file, Geiser uses the following algorithm:
1. If the file-local variable 'geiser-scheme-implementation' is
defined, its value is used. A common way of setting buffer-local
variables is to put them in a comment near the beginning of the
file, surrounded by '-*-' marks, as in:
;; -*- geiser-scheme-implementation: guile -*-
2. If you've customized 'geiser-active-implementations' so that it's a
single-element list, that element is used as the chosen
implementation.
3. The contents of the file is scanned for hints on its associated
implementation. For instance, files that contain a '#lang'
directive will be considered Racket source code, while those with a
'define-module' form in them will be assigned to a Guile REPL.
4. The current buffer's file name is checked against the rules given
in 'geiser-implementations-alist', and the first match is applied.
You can provide your own rules by customizing this variable, as
explained below.
5. If we haven't been lucky this far and you have customized
'geiser-default-implementation' to the name of a supported
implementation, we'll follow your lead.
6. See? That's the problem of being a smart aleck: one's always
outsmarted by people around. At this point, geiser-mode will
humbly give up and ask you to explicitly choose the Scheme
implementation.
As you can see in the list above, there are several ways to influence
Geiser's guessing by means of customizable variables. The most direct
(and most impoverishing) is probably limiting the active implementations
to a single one, while customizing 'geiser-implementations-alist' is the
most flexible (and, unsurprisingly, also the most complex). Here's the
default value for the latter variable:
(((regexp "\\.scm$") guile)
((regexp "\\.ss$") racket)
((regexp "\\.rkt$") racket))
which describes the simple heuristic that files with '.scm' as extension
are by default associated to a Guile REPL while those ending in '.ss' or
'.rkt' correspond to Racket's implementation (with the caveat that these
rules are applied only if the previous heuristics have failed to detect
the correct implementation, and that they'll match only if the
corresponding implementation is active). You can add rules to
'geiser-implementations-alist' (or replace all of them) by customizing
it. Besides regular expressions, you can also use a directory name; for
instance, the following snippet:
(eval-after-load "geiser-impl"
'(add-to-list 'geiser-implementations-alist
'((dir "/home/jao/prj/frob") guile)))
will add a new rule that says that any file inside my
'/home/jao/prj/frob' directory (or, recursively, any of its children) is
to be assigned to Guile. Since rules are first matched, first served,
this new rule will take precedence over the default ones.
A final tip: if you want Geiser to start automatically a REPL for you
if it notices that there's no one active when it enters geiser-mode, you
can customize 'geiser-mode-start-repl-p' to 't'.
Managing multiple scheme projects
.................................
By default, Geiser will re-use a single REPL for all buffers sharing the
same scheme implementation. This works well enough in many cases, but
may become problematic (or at least annoying) when working on multiple
projects with separate dependencies and include paths.
Geiser provides optional support for using separate REPLs for each
project, which can be enabled by customizing
'geiser-repl-current-project-function' and selecting your Emacs
project-management library of choice (eg. 'project.el' or
'projectile'). With this configured, if you want new REPLs to
automatically associate themselves with the current project, so that all
Geiser commands will ignore REPLs that are not associated with the
project, customize the toggle 'geiser-repl-per-project-p' to 't' and
you're all set up.
This can be very convenient when used with a '.dir-locals.el' in the
project root to set include paths, ensuring that Geiser REPLs will
always know where to find your project's modules or dependencies.
Geiser automatically handles the common case of the project root
belonging to the load path: unless you tell it otherwise (using the
customisable flag 'geiser-repl-add-project-path-p', which defaults to
't'), it will add the result of calling
'geiser-repl-current-project-function' to the REPLs load path on
startup.
Switching between source files and the REPL
...........................................
Once you have a working geiser-mode, you can switch from Scheme source
buffers to the REPL or 'C-c C-z'. Those shortcuts map to the
interactive command 'geiser-repl-switch'.
If you use a numeric prefix, as in 'C-u C-c C-z', besides being
teleported to the REPL, the latter will switch to the namespace of the
Scheme source file, as if you had used 'C-c C-m' in the REPL, with the
source file's module as argument; cf. discussion in *note Switching
context::. This command is also bound to 'C-c C-a'.
Once you're in the REPL, the same 'C-c C-z' shortcut will bring you
back to the buffer you jumped from, provided you don't kill the Scheme
process in between. This is why the command is called
geiser-repl-switch instead of switch-to-repl, and what makes it really
handy, if you ask me.
If for some reason you're not happy with the Scheme implementation
that Geiser has assigned to your file, you can change it with 'C-c C-s',
and you probably should take a look at the previous subsection to make
sure that Geiser doesn't get confused again.
A note about context
....................
As explained before (*note Modus operandi::), all Geiser activities take
place in the context of the current namespace, which, for Scheme
buffers, corresponds to the module that the Scheme implementation
associates to the source file at hand (for instance, in Racket, there's
a one-to-one correspondence between paths and modules, while Guile
relies on explicit 'define-module' forms in the source file).
Now that we have 'geiser-mode' happily alive in our Scheme buffers
and communicating with the right REPL instance, let us see what it can
do for us, besides jumping to and fro.
File: geiser.info, Node: Documentation helpers, Next: To eval or not to eval, Prev: The source and the REPL, Up: Between the parens
4.3 Documentation helpers
=========================
Autodoc redux
.............
The first thing you will notice by moving around Scheme source is that,
every now and then, the echo area lights up with the same autodoc
messages we know and love from our REPL forays. This happens every time
the Scheme process is able to recognise an identifier in the buffer, and
provide information either on its value (for variables) or on its arity
and the name of its formal arguments (for procedures and macros). That
information will only be available if the module the identifier belongs
to has been loaded in the running Scheme image. So it can be the case
that, at first, no autodoc is shown for identifiers defined in the file
you're editing. But as soon as you evaluate them (either individually
or collectively using any of the devices described in *note To eval or
not to eval::) their signatures will start appearing in the echo area.
Autodoc activation is controlled by a minor mode, 'geiser-autodoc',
which you can toggle with 'M-x geiser-autodoc-mode', or its associated
keyboard shortcut, 'C-c C-d a'. That /A indicator in the mode-line is
telling you that autodoc is active. If you prefer that it be inactive
by default (e.g., because you're connecting to a really remote scheme
and want to minimize network exchanges), just set
'geiser-mode-autodoc-p' to 'nil' in your customization files. Even when
autodoc mode is off, you can use 'geiser-autodoc-show', bound by default
to 'C-c C-d s', to show the autodoc string for the symbol at point.
The way autodoc displays information deserves some explanation. It
will first show the name of the module where the identifier at hand is
defined, followed by a colon and the identifier itself. If the latter
corresponds to a procedure or macro, it will be followed by a list of
argument names, starting with the ones that are required. Then there
comes a list of optional arguments, if any, enclosed in parentheses.
When an optional argument has a default value (or a form defining its
default value), autodoc will display it after the argument name. When
the optional arguments are keywords, their names are prefixed with "#:"
(i.e., their names are keywords). An ellipsis (...) serves as a marker
of an indeterminate number of parameters, as is the case with rest
arguments or when autodoc cannot fathom the exact number of arguments
(this is often the case with macros defined using 'syntax-case').
Another way in which autodoc displays its ignorance is by using an
underscore to display parameters whose name is beyond its powers.
It can also be the case that a function or macro has more than one
signature (e.g., functions defined using 'case-lambda', or some
'syntax-rules' macros, for which Geiser has often the black magic
necessary to retrieve their actual arities). In those cases, autodoc
shows all known signatures (using the above rules for each one)
separated by a vertical bar (|).
As you have already noticed, the whole autodoc message is enclosed in
parentheses. After all, we're talking about Scheme here.
Finally, life is much easier when your cursor is on a symbol
corresponding to a plain variable: you'll see in the echo area its name,
preceded by the module where it's defined, and followed by its value,
with an intervening arrow for greater effect. This time, there are no
enclosing parentheses (i hope you see the logic in my madness).
You can change the way Geiser displays the module/identifier combo by
customizing 'geiser-autodoc-identifier-format'. For example, if you
wanted a tilde surrounded by spaces instead of a colon as a separator,
you would write something like:
(setq geiser-autodoc-identifier-format "%s ~ %s")
in your Emacs initialisation files. There's also a face
('geiser-font-lock-autodoc-identifier') that you can customize (for
instance, with 'M-x customize-face') to change the appearance of the
text. And another one ('geiser-font-lock-autodoc-current-arg') that
controls how the current argument position is highlighted.
Other documentation commands
............................
Sometimes, autodoc won't provide enough information for you to
understand what a function does. In those cases, you can ask Geiser to
ask the running Scheme for further information on a given identifier or
module.
For symbols, the incantation is 'M-x geiser-doc-symbol-at-point', or
'C-c C-d C-d' for short. If the associated Scheme supports docstrings
(as, for instance, Guile does), you'll be teleported to a new Emacs
buffer displaying Geiser's documentation browser, filled with
information about the identifier, including its docstring (if any;
unfortunately, that an implementation supports docstrings doesn't mean
that they're used everywhere).
Pressing 'q' in the documentation buffer will bring you back,
enlightened, to where you were. There's also a handful of other
navigation commands available in that buffer, which you can discover by
means of its menu or via the good old 'C-h m' command. And feel free to
use the navigation buttons and hyperlinks that justify my calling this
buffer a documentation browser.
For Racket, which does not support docstrings out of the box, this
command will provide less information, but the documentation browser
will display the corresponding contract when it's available, as well as
some other tidbits for re-exported identifiers.
You can also ask Geiser to display information about a module, in the
form of a list of its exported identifiers, using 'C-c C-d C-m', exactly
as you would do in *note the REPL: repl-mod.
In both cases, the documentation browser will show a couple of
buttons giving you access to further documentation. First, you'll see a
button named source: pressing it you'll jump to the symbol's definition.
The second button, dubbed manual, will open the Scheme implementation's
manual page for the symbol at hand. For Racket, that will open your web
browser displaying the corresponding reference's page (using the HTML
browser in Racket's configuration, which you can edit in DrRacket's
preferences dialog, or by setting 'plt:framework-pref:external-browser'
directly in '~/.racket/racket-prefs.rktd'), while in Guile a lookup will
be performed in the texinfo manual.
For Guile, the manual lookup uses the info indexes in the standard
Guile info nodes, which are usually named "guile" or "guile-2.0". If
yours are named differently, just add your name to the customizable
variable 'geiser-guile-manual-lookup-nodes'.
A list of all navigation commands in the documentation browser is
available in *note our cheat-sheet: Documentation browser.
You can also skip the documentation browser and jump directly to the
manual page for the symbol at point with the command
'geiser-doc-look-up-manual', bound to 'C-c C-d i'.
File: geiser.info, Node: To eval or not to eval, Next: To err perchance to debug, Prev: Documentation helpers, Up: Between the parens
4.4 To eval or not to eval
==========================
One of Geiser's main goals is to facilitate incremental development.
You might have noticed that i've made a big fuss of Geiser's ability to
recognize context, by dint of being aware of the namespace where its
operations happen.
That awareness is especially important when evaluating code in your
scheme buffers, using the commands described below. They allow you to
send code to the running Scheme with a granularity ranging from whole
files to single s-expressions. That code will be evaluated in the
module associated with the file you're editing, allowing you to redefine
values and procedures to your heart's (and other modules') content.
Macros are, of course, another kettle of fish: one needs to
re-evaluate uses of a macro after redefining it. That's not a
limitation imposed by Geiser, but a consequence of how macros work in
Scheme (and other Lisps). There's also the risk that you lose track of
what's actually defined and what's not during a given session. But, in
my opinion
(https://jaortega.wordpress.com/2009/03/29/from-my-cold-prying-hands),
those are limitations we lispers are aware of, and they don't force us
to throw the baby with the bathwater and ditch incremental evaluation.
Some people disagree; if you happen to find their arguments
(https://blog.racket-lang.org/2009/03/the-drscheme-repl-isnt-the-one-in-emacs.html)
convincing, you don't have to throw away Geiser together with the baby:
'M-x geiser-restart-repl' will let you restart the REPL as many times as
you see fit. Moreover, you can invoke 'geiser-compile-current-buffer'
and 'geiser-load-current-buffer' with a prefix argument (that'd be
something like 'C-u C-c C-k' for compilation, for instance), to tell
Geiser to restart the REPL associated with a buffer before compiling or
loading its current contents.
For all of you auld bearded lispers still with me, here are some of
the commands performing incremental evaluation in Geiser.
'geiser-eval-last-sexp', bound to 'C-x C-e', will eval the
s-expression just before point. If you use a prefix, as in 'C-u C-x
C-e', besides evaluating it the expression is inserted in the the
buffer.
'geiser-eval-definition', bound to 'C-M-x', finds the topmost
definition containing point and sends it for evaluation. The variant
'geiser-eval-definition-and-go' ('C-c M-e') works in the same way, but
it also teleports you to REPL after the evaluation.
'geiser-eval-region', bound to 'C-c C-r', evals the current region.
Again, there's an and-go version available, 'geiser-eval-region-and-go',
bound to 'C-c M-r'. And, if you want to extend the evaluated region to
the whole buffer, there is 'geiser-eval-buffer', bound to 'C-c C-b' and
its companion 'geiser-eval-buffer-and-go', bound to 'C-c M-b'.
For all the commands above, the result of the evaluation is displayed
in the minibuffer, unless it causes a (Scheme-side) error (*note To err
perchance to debug::), or, for schemes supporting them (such as Racket),
the evaluation yields an image, in which case you'll see it in popping
up in the Geiser debug buffer (if your Emacs runs under the auspices of
a graphical toolkit), or via an external viewer if you set
'geiser-image-viewer' to the path of an appropriate visualization
program (see also *note Seeing is believing:: for more on image
support).
At the risk of repeating myself, i'll remind you that all these
evaluations will take place in the namespace of the module corresponding
to the Scheme file from which you're sending your code, which, in
general, will be different from the REPL's current module. And, if all
goes according to plan, (re)defined variables and procedures should be
immediately visible inside and, if exported, outside their module.
Besides evaluating expressions, definitions and regions, you can also
macro-expand them. The corresponding key bindings start with the prefix
'C-c C-m' and end, respectively, with 'C-e', 'C-x' and 'C-r'. The
result of the macro expansion always appears in a pop up buffer.
All the evaluations and expansions performed by the commands above
are asynchronous(1), so that you can move around while the answer is
being computed. The command 'geiser-eval-interrupt', bound to 'C-c C-i'
will interrupt any on-going evaluation and, when the scheme
implementation supports a debugger, bring you to a buffer where you can
perform buffer actions in the interrupted evaluation's context.
Oh, didn't i mention we have support for debuggers? Let's talk about
that next.
---------- Footnotes ----------
(1) For local REPLs, where we can easily send an interrupt signal to
the scheme process; remote REPLs are another kettle of fish in this
regard, and generally interruptions are supported: you'll just have to
kill the connection if caught in a loop.
File: geiser.info, Node: To err perchance to debug, Next: Jumping around, Prev: To eval or not to eval, Up: Between the parens
4.5 To err: perchance to debug
==============================
When an error occurs during evaluation, it will be reported according to
the capabilities of the underlying Scheme REPL.
In most schemes, you'll be presented with a backtrace, in a new
buffer where file paths locating the origin of the error are click-able
(you can navigate them using the <TAB> key, and use <RET> or the mouse
to jump to the offending spot; or invoke Emacs' stock commands
'next-error' and 'previous-error', bound to 'M-g n' and 'M-g p' by
default).
By default, Geiser will tele-transport your pointer to the debug
buffer: if you prefer to stay in the source buffer, set
'geiser-debug-jump-to-debug' to nil.
For schemes with good debug support (Guile is one), the debug buffers
offer a debugging menu, accesible via the ',' (that's a comma) key. If
you press it, a transient menu will appear, offering you a variety of
actions, including showing local variable values or a more detailed
backtrace or frame display. This is the same interface you'll encounter
the in case of interrupted evaluations, either by your explicit 'C-c
C-i' command or because a breakpoint has been previosuly set.
In addition, Geiser will sometimes report warnings for otherwise
successful evaluations. In those cases, it won't enter the debugger,
just report the warnings in a debug buffer.
File: geiser.info, Node: Jumping around, Next: Geiser writes for you, Prev: To err perchance to debug, Up: Between the parens
4.6 Jumping around
==================
This one feature is as sweet as it is easy to explain: 'M-.'
('geiser-edit-symbol-at-point') will open the file where the identifier
around point is defined and land your point on its definition. To
return to where you were, press 'M-,' ('geiser-pop-symbol-stack'). This
command works also for module names: Geiser first tries to locate a
definition for the identifier at point and, if that fails, a module with
that name; if the latter succeeds, the file where the module is defined
will pop up.
Sometimes, the underlying Scheme will tell Geiser only the file where
the symbol is defined, but Geiser will use some heuristics (read,
regular expressions) to locate the exact line and bring you there.
Thus, if you find Geiser systematically missing your definitions, send a
message to the mailing list <geiser-users@nongnu.org>, and we'll try to
make the algorithm smarter.
You can control how the destination buffer pops up by setting
'geiser-edit-symbol-method' to either 'nil' (to open the file in the
current window), ''window' (other window in the same frame) or ''frame'
(in a new frame).
File: geiser.info, Node: Geiser writes for you, Prev: Jumping around, Up: Between the parens
4.7 Geiser writes for you
=========================
No self-respecting programming mode would be complete without
completion. In geiser-mode, identifier completion is bound to
'M-<TAB>', and will offer all visible identifiers starting with the
prefix before point. Visible here means all symbols imported or defined
in the current namespace plus locally bound ones. E.g., if you're at
the end of the following partial expression:
(let ((default 42))
(frob def
and press 'M-<TAB>', one of the possible completions will be 'default'.
After obtaining the list of completions from the running Scheme,
Geiser uses the standard Emacs completion machinery to display them.
That means, among other things, that partial completion is available:
just try to complete 'd-s' or 'w-o-t-s' to see why this is a good thing.
Partial completion won't work if you have disabled it globally in your
Emacs configuration: if you don't know what i'm talking about, never
mind: Geiser's partial completion will work for you out of the box.
If you find the 'M' modifier annoying, you always have the option to
activate 'geiser-smart-tab-mode', which will make the <TAB> key double
duty as the regular Emacs indentation command (when the cursor is not
near a symbol) and Geiser's completion function. If you want this
smarty pants mode always on in Scheme buffers, customize
'geiser-mode-smart-tab-p' to 't'.
Geiser also knows how to complete module names: if no completion for
the prefix at point is found among the currently visible bindings, it
will try to find a module name that matches it. You can also request
explicitly completion only over module names using 'M-`' (that's a
backtick).
Besides completion, there's also this little command,
'geiser-squarify', which will toggle the delimiters of the innermost
list around point between round and square brackets. It is bound to
'C-c C-e ['. With a numeric prefix (as in, say, 'M-2 C-c C-e ['), it
will perform that many toggles, forward for positive values and backward
for negative ones.
Caveat about completion
-----------------------
It is possible for Geiser to hang your Emacs process when trying to
complete symbols. This can happen in the REPL itself or even in a
Scheme buffer that is attached to the REPL process. For more details on
how to fix this problem, *note Caveat about completion & the REPL:
completion-caveat.
File: geiser.info, Node: Cheat sheet, Next: No hacker is an island, Prev: Between the parens, Up: Top
5 Cheat sheet
*************
In the tables below, triple chords always accept a variant with the
third key not modified by <Control>; e.g., 'geiser-autodoc-show' is
bound both to 'C-c C-d C-s' and 'C-c C-d s'.
* Menu:
* Scheme buffers::
* REPL::
* Documentation browser::
File: geiser.info, Node: Scheme buffers, Next: REPL, Prev: Cheat sheet, Up: Cheat sheet
5.1 Scheme buffers
==================
Key Command Description
---------------------------------------------------------------------------
C-c C-z 'geiser-mode-switch-to-repl' Switch to REPL
C-c C-a 'geiser-mode-switch-to-repl-and-enter'Switch to REPL and current
module (also 'C-u C-c C-z')
C-c C-s 'geiser-set-scheme' Specify Scheme
implementation for buffer
M-. 'geiser-edit-symbol-at-point' Go to definition of
identifier at point
M-, 'geiser-pop-symbol-stack' Go back to where M-. was
last invoked
C-c C-e C-m 'geiser-edit-module' Ask for a module and open
its file
C-c C-e C-l 'geiser-add-to-load-path' Ask for a directory and add
to Scheme load path
C-c C-e C-[ 'geiser-squarify' Toggle between () and []
for current form
C-c C-\ 'geiser-insert-lambda' Insert greek lambda or,
with prefix, a lambda form
C-c C-i 'geiser-eval-interrupt' Interrupt ongoing
evaluation
C-M-x 'geiser-eval-definition' Eval definition around
point
C-c C-c 'geiser-eval-definition' Eval definition around
point
C-c M-e 'geiser-eval-definition-and-go'Eval definition around
point and switch to REPL
C-c M-c 'geiser-eval-definition-and-go'Eval definition around
point and switch to REPL
C-x C-e 'geiser-eval-last-sexp' Eval sexp before point
C-c C-r 'geiser-eval-region' Eval region
C-c M-r 'geiser-eval-region-and-go' Eval region and switch to
REPL
C-c C-b 'geiser-eval-buffer' Eval buffer
C-c M-b 'geiser-eval-buffer-and-go' Eval buffer and switch to
REPL
C-c C-m C-x 'geiser-expand-definition' Macro-expand definition
around point
C-c C-m C-e 'geiser-expand-last-sexp' Macro-expand sexp before
point
C-c C-m C-r 'geiser-expand-region' Macro-expand region
C-c C-k 'geiser-compile-current-buffer'Compile and load current
file; with prefix, restart
REPL before
C-c C-l 'geiser-load-file' Load scheme file
M-g n, C-x ' 'next-error' Jump to the location of
next error
M-g p 'previous-error' Jump to the location of
previous error
C-c C-d C-d 'geiser-doc-symbol-at-point' See documentation for
identifier at point
C-c C-d C-s 'geiser-autodoc-show' Show signature or value for
identifier at point in echo
area
C-c C-d C-m 'geiser-doc-module' See a list of a module's
exported identifiers
C-c C-d C-i 'geiser-doc-look-up-manual' Look up manual for symbol
at point
C-c C-d C-a 'geiser-autodoc-mode' Toggle autodoc mode
C-c < 'geiser-xref-callers' Show callers of procedure
at point
C-c > 'geiser-xref-callees' Show callees of procedure
at point
M-TAB 'completion-at-point' Complete identifier at
point
M-', C-. 'geiser-capf-complete-module' Complete module name at
point
File: geiser.info, Node: REPL, Next: Documentation browser, Prev: Scheme buffers, Up: Cheat sheet
5.2 REPL
========
Key Command Description
---------------------------------------------------------------------------
C-c C-z 'geiser-repl-switch' Start Scheme REPL, or jump
to previous buffer
C-c M-o 'geiser-repl-clear-buffer' Clear REPL buffer
C-c C-k 'geiser-repl-interrupt' Interrupt REPL evaluation
(signalling inferior
scheme)
C-c C-q 'geiser-repl-exit' Kill Scheme process
M-. 'geiser-edit-symbol-at-point' Edit identifier at point
C-c C-l 'geiser-load-file' Load scheme file
TAB 'geiser-repl-tab-dwim' Complete, indent, or go to
next error
S-TAB 'geiser-repl--previous-error' Go to previous error in the
(backtab) REPL buffer
M-TAB 'completion-at-point' Complete identifier at
point
M-', C-. 'geiser-capf-complete-module' Complete module name at
point
C-c [, C-c 'geiser-squarify' Toggle between () and []
C-[ for current form
C-c \, C-c 'geiser-insert-lambda' Insert greek lambda or,
C-\ with prefix, a lambda form
C-c C-r 'geiser-add-to-load-path' Ask for a directory and add
to Scheme load path
M-p, M-n (comint commands) Prompt history, matching
current prefix
C-c M-p, C-c (comint commands) Previous/next prompt inputs
M-n
C-c C-m 'geiser-repl-switch-to-module'Set current module
C-c C-i 'geiser-repl-import-module' Import module into current
namespace
C-c C-d C-d 'geiser-doc-symbol-at-point' See documentation for
symbol at point
C-c C-d C-i 'geiser-doc-look-up-manual' Look up manual for symbol
at point
C-c C-d C-m 'geiser-repl--doc-module' See documentation for
module
C-c C-d C-a 'geiser-autodoc-mode' Toggle autodoc mode
File: geiser.info, Node: Documentation browser, Prev: REPL, Up: Cheat sheet
5.3 Documentation browser
=========================
Key Command Description
---------------------------------------------------------------------------
TAB, n 'forward-button' Next link
S-TAB, p 'backward-button' Previous link
N 'geiser-doc-next-section' Next section
P 'geiser-doc-previous-section' Previous section
f 'geiser-doc-next' Next page
b 'geiser-doc-previous' Previous page
k 'geiser-doc-kill-page' Kill current page and go to
previous or next
g, r 'geiser-doc-refresh' Refresh page
c 'geiser-doc-clean-history' Clear browsing history
., M-. 'geiser-doc-edit-symbol-at-point'Edit identifier at point
z 'geiser-doc-switch-to-repl' Switch to REPL
q 'View-quit' Bury buffer
File: geiser.info, Node: No hacker is an island, Next: Index, Prev: Cheat sheet, Up: Top
6 No hacker is an island
************************
Dan Leslie, with the help of his three-months old daughter Freija,
proved there's a smidgen of sense in this madness by adding support for
Chicken to version 0.7 of Geiser, several years after it was born. And
Peter Feigl reinforced that feeling soon afterwards with his work on
supporting GNU/MIT Scheme, Chib and Chez in one fell swoop.
Andy Wingo, Geiser's first user, has been a continuous source of
encouragement and suggestions, and keeps improving Guile and heeding my
feature requests.
The nice thing about collaborating with Andreas Rottmann over all
these years is that he will not only make your project better with
insightful comments and prodding: he'll send you patches galore too.
Ludovic Courtès, #geiser's citizen no. 1, joined the fun after a
while, and has since then been a continuous source of encouragement,
ideas and bug reports.
Michael Wilber convinced me that image support for Racket was not
only fun, but easy, with the best argument: actual code!
Daniel Hackney and Grant Rettke created the first ELPA packages for
Geiser and taught me to fish.
Diogo F. S. Ramos is Geiser's most indefatigable user and bug
reporter, and the mailing list has been a far less lonely place since he
came.
Aleix Conchillo has been my favourite spammer, beta tester and patch
sender during more years and for more projects than i can remember.
Philip K. prepared the NonGNU ELPA packages for Geiser, making them
available by default starting in Emacs 28, very generously volunteering
all the work (i just had to update the docs!).
Jonas Bernoulli, as it's his indefatigable wont, has improved
Geiser's compliance to current Emacs packaging standards, making it a
respectful member of the ELPA community.
Eduardo Cavazos' contagious enthusiasm has helped in many ways to
keep Geiser alive, and he's become its best evangelist in R6RS circles.
Alex Kost has contributed with many bug reports and improved Geiser
with several patches.
Eli Barzilay took the time to play with an early alpha and made many
valuable suggestions, besides answering all my 'how do you in PLT'
questions.
Matthew Flatt, Robby Findler and the rest of the PLT team did not
only answer my inquiries, but provided almost instant fixes to the few
issues i found.
Thanks also to the PLT and Guile communities, for showing me that
Geiser was not only possible, but a pleasure to hack on. And to the
Slime hackers, who led the way.
Joining the fun
...............
* For questions, praise, critique and anything else Geiser, do not
hesitate to drop an email to our list, (@ geiser-users (. nongnu
org)) (mailto:geiser-users@nongnu.org): no subscription required.
Check the list page
(http://lists.nongnu.org/mailman/listinfo/geiser-users) for more
information or browse the archives
(http://lists.nongnu.org/archive/html/geiser-users/). The list is
also accessible via Gmane (http://gmane.org) as
gmane.lisp.scheme.geiser
(http://dir.gmane.org/gmane.lisp.scheme.geiser).
* You can submit bug reports either to the mailing list or to our bug
tracker (https://gitlab.com/groups/emacs-geiser/-/issues) over at
Gitlab.
* The Freenode IRC channel #geiser is the Geiserati's meeting point
in cyberspace.
File: geiser.info, Node: Index, Prev: No hacker is an island, Up: Top
Index
*****
[index ]
* Menu:
* ,enter vs. enter!: Switching context. (line 6)
* ac-geiser: Friends. (line 9)
* ask on kill, don't: Customization and tips.
(line 133)
* autocomplete: Friends. (line 9)
* autodoc customized: Documentation helpers.
(line 64)
* autodoc explained: Documentation helpers.
(line 32)
* autodoc for variables: Documentation helpers.
(line 58)
* autodoc, disabling: Customization and tips.
(line 115)
* autodoc, in scheme buffers: Documentation helpers.
(line 9)
* autodoc, in the REPL: Autodoc and friends. (line 11)
* autostart REPL: The source and the REPL.
(line 80)
* backtraces: To err perchance to debug.
(line 6)
* bug tracker: No hacker is an island.
(line 76)
* company: Friends. (line 9)
* completion for module names: Geiser writes for you.
(line 33)
* completion in scheme buffers: Geiser writes for you.
(line 6)
* completion, at the REPL: Completion and error handling.
(line 6)
* connect to server: Starting the REPL. (line 43)
* corpses: Top. (line 63)
* current module: Modus operandi. (line 15)
* current module, change: Switching context. (line 21)
* current module, in REPL: Switching context. (line 6)
* default directory: Customization and tips.
(line 69)
* derailment: Top. (line 63)
* dir-locals: The source and the REPL.
(line 87)
* disabling autodoc: Documentation helpers.
(line 22)
* docstrings, maybe: Documentation helpers.
(line 85)
* documentation for symbol: Documentation helpers.
(line 85)
* ELPA: The quick and easy way.
(line 6)
* error buffer: To err perchance to debug.
(line 9)
* evaluating images: To eval or not to eval.
(line 56)
* evaluation: To eval or not to eval.
(line 37)
* external image viewer: Seeing is believing. (line 10)
* faces, in the REPL: Starting the REPL. (line 35)
* geiser-add-to-load-path: Customization and tips.
(line 58)
* geiser-mode: Activating Geiser. (line 6)
* geiser-mode commands: Activating Geiser. (line 21)
* geiser-repl-add-project-path-p: The source and the REPL.
(line 102)
* geiser-repl-add-project-paths: Customization and tips.
(line 58)
* geiser-repl-per-project-p: The source and the REPL.
(line 92)
* gmane: No hacker is an island.
(line 66)
* Guile info nodes: Documentation helpers.
(line 120)
* Guile's REPL server: Starting the REPL. (line 48)
* GUILE_LOAD_COMPILED_PATH: Customization and tips.
(line 58)
* GUILE_LOAD_PATH: Customization and tips.
(line 58)
* help on identifier: Autodoc and friends. (line 29)
* host, default: Customization and tips.
(line 124)
* image cache: Seeing is believing. (line 16)
* image display: To eval or not to eval.
(line 56)
* image support: Seeing is believing. (line 6)
* image viewer: Seeing is believing. (line 10)
* incremental development: To eval or not to eval.
(line 6)
* incremental development, evil: To eval or not to eval.
(line 18)
* incremental development, not evil: To eval or not to eval.
(line 37)
* interrupt evaluation: To eval or not to eval.
(line 78)
* IRC channel: No hacker is an island.
(line 79)
* jump, at the REPL: Autodoc and friends. (line 51)
* jumping customized: Jumping around. (line 22)
* jumping in scheme buffers: Jumping around. (line 6)
* macrostep: Friends. (line 9)
* mailing list: No hacker is an island.
(line 66)
* manual autodoc: Documentation helpers.
(line 22)
* module exports: Autodoc and friends. (line 39)
* modus operandi: Modus operandi. (line 6)
* NonGNU ELPA: The quick and easy way.
(line 6)
* opening manual pages: Documentation helpers.
(line 128)
* paredit: Friends. (line 9)
* partial completion: Geiser writes for you.
(line 18)
* peace and quiet: Customization and tips.
(line 115)
* philosophy: Top. (line 63)
* philosophy <1>: To eval or not to eval.
(line 6)
* port, default: Customization and tips.
(line 124)
* project.el: The source and the REPL.
(line 87)
* projectile: The source and the REPL.
(line 87)
* projects: The source and the REPL.
(line 87)
* quick install: The quick and easy way.
(line 6)
* Racket's REPL server: Starting the REPL. (line 53)
* recursion: Index. (line 6)
* remote connections: Starting the REPL. (line 78)
* remote REPL: Starting the REPL. (line 43)
* REPL: Starting the REPL. (line 6)
* REPL commands: First aids. (line 6)
* REPL customization: Customization and tips.
(line 6)
* REPL, faces: Starting the REPL. (line 35)
* scheme binary: Customization and tips.
(line 38)
* scheme executable path: Customization and tips.
(line 38)
* scheme file extensions: Activating Geiser. (line 38)
* scheme implementation, choosing: Customization and tips.
(line 20)
* scheme implementation, choosing <1>: The source and the REPL.
(line 21)
* scheme init file: Customization and tips.
(line 58)
* scheme load path: Customization and tips.
(line 58)
* smart tabs: Geiser writes for you.
(line 26)
* start REPL, automatically: The source and the REPL.
(line 80)
* startup timeout: Customization and tips.
(line 85)
* supported versions: Must needs. (line 6)
* swanking: Showing off. (line 6)
* switching schemes: The source and the REPL.
(line 131)
* switching to module: The source and the REPL.
(line 119)
* switching to REPL: The source and the REPL.
(line 115)
* switching to source: The source and the REPL.
(line 115)
* thanks: No hacker is an island.
(line 6)
* timeout: Customization and tips.
(line 85)
* to err is schemey: To err perchance to debug.
(line 6)
* useless wretch: Activating Geiser. (line 43)
* Version checking: Customization and tips.
(line 50)
* versions supported: Must needs. (line 6)
Tag Table:
Node: Top907
Node: Introduction2668
Node: Modus operandi3002
Ref: current-module3657
Node: Showing off5122
Node: Installation6400
Node: Must needs6613
Node: The quick and easy way8295
Ref: The quick and easy way-Footnote-19773
Node: From the source's mouth9928
Node: Friends10713
Ref: paredit10987
Node: The REPL12124
Ref: quick-start12243
Node: Starting the REPL12634
Node: First aids17013
Node: Switching context18846
Node: Completion and error handling20776
Ref: completion-caveat22484
Node: Autodoc and friends24398
Ref: repl-mod26468
Node: Seeing is believing27474
Node: Customization and tips28486
Ref: choosing-impl29215
Ref: active-implementations29446
Ref: impl-binary29828
Node: Between the parens34239
Node: Activating Geiser35301
Node: The source and the REPL37911
Ref: repl-association38951
Ref: repl-per-project42199
Ref: switching-repl-buff43612
Node: Documentation helpers45301
Ref: doc-browser49569
Node: To eval or not to eval52296
Ref: To eval or not to eval-Footnote-157040
Node: To err perchance to debug57293
Node: Jumping around58796
Node: Geiser writes for you60073
Node: Cheat sheet62577
Node: Scheme buffers62961
Node: REPL67399
Node: Documentation browser69986
Node: No hacker is an island71054
Node: Index74506
End Tag Table
Local Variables:
coding: utf-8
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