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| -rw-r--r-- | doc/guix.texi | 37 |
1 files changed, 35 insertions, 2 deletions
diff --git a/doc/guix.texi b/doc/guix.texi index a20e54f8ae..b7f1bc1f00 100644 --- a/doc/guix.texi +++ b/doc/guix.texi @@ -6908,11 +6908,44 @@ The @code{alist-delete} call above removes the tuple from the (@pxref{SRFI-1 Association Lists,,, guile, GNU Guile Reference Manual}). +In some cases, you may find it useful to write functions +(``procedures'', in Scheme parlance) that return a package based on some +parameters. For example, consider the @code{luasocket} library for the +Lua programming language. We want to create @code{luasocket} packages +for major versions of Lua. One way to do that is to define a procedure +that takes a Lua package and returns a @code{luasocket} package that +depends on it: + +@lisp +(define (make-lua-socket name lua) + ;; Return a luasocket package built with LUA. + (package + (name name) + (version "3.0") + ;; several fields omitted + (inputs + `(("lua" ,lua))) + (synopsis "Socket library for Lua"))) + +(define-public lua5.1-socket + (make-lua-socket "lua5.1-socket" lua-5.1)) + +(define-public lua5.2-socket + (make-lua-socket "lua5.2-socket" lua-5.2)) +@end lisp + +Here we have defined packages @code{lua5.1-socket} and +@code{lua5.2-socket} by calling @code{make-lua-socket} with different +arguments. @xref{Procedures,,, guile, GNU Guile Reference Manual}, for +more info on procedures. Having top-level public definitions for these +two packages means that they can be referred to from the command line +(@pxref{Package Modules}). + @cindex package transformations These are pretty simple package variants. As a convenience, the @code{(guix transformations)} module provides a high-level interface -that directly maps to package transformation options (@pxref{Package -Transformation Options}): +that directly maps to the more sophisticated package transformation +options (@pxref{Package Transformation Options}): @deffn {Scheme Procedure} options->transformation @var{opts} Return a procedure that, when passed an object to build (package, |