@node Fun between the parens
@chapter Fun 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 (specially if you use @ref{paredit,,Paredit}).
Geiser's support for writing Scheme code adds to Emacs'
@code{scheme-mode}, rather than supplanting it; and it does so by means
of a minor mode (unimaginatively dubbed @code{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::
* Autodoc redux::
* Evaluating Scheme code::
* Geiser writes for you::
* In good company::
@end menu

@node Activating Geiser, The source and the REPL, Fun between the parens, Fun between the parens
@section Activating Geiser
@img{geiser-mode, right} With Geiser installed following any of the
procedures described in @ref{Setting it up}, Emacs will automatically
activate @i{geiser-mode} when opening a Scheme buffer. Geiser also
instructs Emacs to consider files with the extension @file{rkt} Scheme
files, 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 everthing 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 (@kbd{M-x customize-group @key{RET}
geiser}): there's lot of fine tunning available there.

Since @i{geiser-mode} is a minor mode, you can toggle it with
@kbd{M-x geiser-mode}, and control its activation in hooks with the
functions @code{turn-on-geiser-mode} and @code{turn-off-geiser-mode}.
If, for some reason i cannot fathom, you prefer @i{geiser-mode} not
to be active by default, the following elisp incantation will do the
trick:
@example
(eval-after-load "geiser-mode"
  (remove-hook 'scheme-mode-hook 'turn-on-geiser-mode))
@end example
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:
@example
(add-to-list 'auto-mode-alist '("\\.funky-extension\\'" . scheme-mode))
@end example

Now, @i{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 all these things happen.

@node The source and the REPL, Autodoc redux, Activating Geiser, Fun between the parens
@section The source and the REPL

@node Autodoc redux, Evaluating Scheme code, The source and the REPL, Fun between the parens
@section Autodoc redux

@node Evaluating Scheme code, Geiser writes for you, Autodoc redux, Fun between the parens
@section Evaluating Scheme code

@node Geiser writes for you, In good company, Evaluating Scheme code, Fun between the parens
@section Geiser writes for you

@node In good company,  , Geiser writes for you, Fun between the parens
@section In good company

@c Local Variables:
@c mode: texinfo
@c TeX-master: "geiser"
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