GNU Emacs and Scheme talk to each other
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-*- mode: org -*-


Geiser is a generic Emacs/Scheme interaction mode, featuring an enhanced REPL and a set of minor modes improving Emacs’ basic scheme major mode. The main functionalities provided are:

  • Evaluation of forms in the namespace of the current module.
  • Macro expansion.
  • File/module loading.
  • 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 (list of evaluation/compilation error in an Emacs’ compilation-mode buffer).
  • Support for inline images in schemes, such as Racket, that treat them as first order values.

NOTE: if you’re not in a hurry, Geiser’s website ( contains a nicer manual, also included in Geiser tarballs as a texinfo file (doc/


Geiser needs Emacs 23.2 or better, and at least one of the supported scheme implementations:

  • Guile 2.0 or better.
  • PLT Racket 6.0 or better.
  • Chicken 4.8.0 or better.
  • MIT/GNU Scheme 9.1.1 or better.
  • Chibi 0.7.3 or better.
  • Chez 9.4 or better.


The easiest way is to use MELPA, and just type `M-x install-package RET geiser` inside emacs.

Geiser can be used either directly from its uninstalled source tree or byte-compiled and installed after performing the standard configure/make/make install dance. See the INSTALL file for more details.

Chicken Addendum

These steps are necessary to fully support Chicken Scheme, but are not required for any other scheme.

Basic configuration

The loading invocations above install all supported Scheme implementations. You can list explicitly the ones that you want by setting the variable `geiser-active-implementations’ before loading geiser.el. For instance:

(setq geiser-active-implementations ‘(chicken guile))

On opening a scheme file, Geiser will try to guess its Scheme, defaulting to the first in the list. Use `C-c C-s’ to select the implementation by hand (on a per file basis).

Check the geiser customization group for some options with:

M-x customize-group RET geiser RET

In particular, customize `geiser-<impl>-binary’, which should point to an executable in your path.

To start a REPL, M-x geiser.

Completion with company-mode

Geiser offers identifier and module name completion, bound to M-TAB and M-` respectively. Only names visible in the current module are offered.

While that is cool and all, things are even better: if you have company-mode ( installed, Geiser’s completion will use it. Just require company-mode and, from then on, any new scheme buffer or REPL will use it.

Quick key reference

In Scheme buffers:

C-c C-zSwitch to REPL
C-c C-aSwitch to REPL and current module
C-c C-sSpecify Scheme implementation for buffer
M-.Go to definition of identifier at point
M-,Go back to where M-. was last invoked
C-c C-e mAsk for a module and open its file
C-c C-e C-lAdd a given directory to Scheme’s load path
C-c C-e [Toggle between () and [] for current form
C-M-xEval definition around point
C-c C-cEval definition around point
C-c M-eEval definition around point and switch to REPL
C-x C-eEval sexp before point
C-c C-rEval region
C-c M-rEval region and switch to REPL
C-c C-bEval buffer
C-c M-bEval buffer and switch to REPL
C-c C-m xMacro-expand definition around point
C-c C-m eMacro-expand sexp before point
C-c C-m rMacro-expand region
C-c C-kCompile and load current file
C-c C-lLoad scheme file
C-c C-d dSee documentation for identifier at point
C-c C-d sSee short documentation for identifier at point
C-c C-d iLook up manual for identifier at point
C-c C-d mSee a list of a module’s exported identifiers
C-c C-d aToggle autodoc mode
C-c <Show callers of procedure at point
C-c >Show callees of procedure at point
M-TABComplete identifier at point
M-`, C-.Complete module name at point
TABComplete identifier at point or indent
(If `geiser-mode-smart-tab-p’ is t)

In the REPL

C-c C-zStart Scheme REPL, or jump to previous buffer
C-c M-oClear scheme output
C-c C-qKill Scheme process
C-c C-lLoad scheme file
C-c C-kNuke REPL: use it if the REPL becomes unresponsive
M-.Edit identifier at point
TAB, M-TABComplete identifier at point
M-`, C-.Complete module name at point
M-p, M-nPrompt history, matching current prefix
C-c C-mSet current module
C-c C-iImport module into current namespace
C-c C-rAdd a given directory to scheme’s load path
C-c C-d C-dSee documentation for symbol at point
C-c C-d C-mSee documentation for module
C-c C-d C-aToggle autodoc mode

In the documentation browser:

fNext page
bPrevious page
TAB, nNext link
S-TAB, pPrevious link
NNext section
PPrevious section
kKill current page and go to previous or next
g, rRefresh page
cClear browsing history
., M-.Edit identifier at point
zSwitch to REPL
qBury buffer

In backtrace (evaluation/compile result) buffers:

  • M-g n, M-g p, C-x ` for error navigation.
  • q to bury buffer.