Complete the documentation on the Gambit backend

INSTALL.md

@@ -1,7 +1,7 @@
 # Installation
 
 Idris 2 is built using Idris, and provides support for two default code
-generation targets: Chez Scheme, and Racket. To build from source, it requires
+generation targets: Chez Scheme, Racket, and Gambit. To build from source, it requires
 at least Idris version 1.3.2 (see https://www.idris-lang.org/pages/download.html). You
 can also build from the generated C.
 
@@ -64,7 +64,7 @@ you run `./configure --threads` to build multithreading support in.
 
 ### Chicken
 
-Chicken scheme offers binary distributions (and source tar balls) from
+Chicken Scheme offers binary distributions (and source tar balls) from
 
 + https://code.call-cc.org/
 
@@ -87,3 +87,14 @@ The following packages are required in order to run Idris:
 - math-lib
 
 These can be installed with `raco setup` and `raco pkg install`.
+
+### Gambit
+
+Gambit Scheme offers binary releases and source tarballs on
+http://gambitscheme.org.
+
+GNU/Linux users can usually find a package on their distribution under one of
+the following names: `gambit`, `gambit-c` or `gambc`.
+
+The default backend of Gambit is C, so you are expected to have a C compiler
+(GCC preferred).

Notes/Directives.md

@@ -112,7 +112,7 @@ Syntax:
 The given instructions are passed directly to the code generator, to be
 interpreted in a backend-specific way.
 
-Currently known backends are: `chez`, `chicken` and `racket`.
+Currently known backends are: `chez`, `chicken`, `racket` and `gambit`.
 
 ## Backend Specific Directives
 

docs/source/backends/gambit.rst

@@ -0,0 +1,36 @@
+****************************
+Gambit Scheme Code Generator
+****************************
+
+The Gambit Scheme code generator can be accessed via the REPL command:
+
+::
+
+    Main> :set cg gambit
+
+Ergo, to run Idris programs with this generator, you will need to install
+`Gambit Scheme <https://gambitscheme.org>`_. Gambit Scheme is free software,
+and available via most pacakge managers.
+
+You can compile an expression ``expr`` of type ``IO ()`` to an executable as
+follows, at the REPL:
+
+::
+
+    Main> :c execname expr
+
+...where ``execname`` is the name of the executable file. This will generate
+the following:
+
+* An executable binary ``build/exec/execname`` of the program.
+* A Gambit Scheme source file ``build/exec/execname.scm``, from which the
+  binary is generated.
+
+You can also execute an expression directly:
+
+::
+
+    Main> :exec expr
+
+Again, ``expr`` must have type ``IO ()``. This will generate a temporary
+Scheme file, and execute the Gambit interpreter on it.

docs/source/updates/updates.rst

@@ -646,8 +646,9 @@ Chez Scheme target
 ------------------
 
 The default code generator is, for the moment, `Chez Scheme
-<https://www.scheme.com/>`_. A Racket code generator is also available. There
-is not yet a way to plug in code generators as in Idris 1, but this is coming.
+<https://www.scheme.com/>`_. Racket and Gambit code generators are also
+available. There is not yet a way to plug in code generators as in Idris 1,
+but this is coming.
 To change the code generator, you can use the ``:set cg`` command:
 
 ::