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| author | Ludovic Courtès <ludo@gnu.org> | 2015-08-26 11:28:23 +0200 |
|---|---|---|
| committer | Ludovic Courtès <ludo@gnu.org> | 2015-08-27 00:49:23 +0200 |
| commit | c2b8467645bb2c2e17eb9c580f39e345c4dc2f4a (patch) | |
| tree | 754462cfbcccdb8c58f000ee5bf88d064279b657 /doc | |
| parent | f7283db37d58f1a7dede5f410c6c0a75aa82b12e (diff) | |
gexp: Add 'lower-object'.
* guix/gexp.scm (lower-object): New procedure.
(lower-inputs, lower-references, gexp->sexp): Use it.
* tests/gexp.scm ("lower-object"): New test.
* doc/guix.texi (G-Expressions): Document it.
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/guix.texi | 18 |
1 files changed, 17 insertions, 1 deletions
diff --git a/doc/guix.texi b/doc/guix.texi index f05376efcf..39093a9c98 100644 --- a/doc/guix.texi +++ b/doc/guix.texi @@ -3125,9 +3125,11 @@ and these dependencies are automatically added as inputs to the build processes that use them. @end itemize +@cindex lowering, of high-level objects in gexps This mechanism is not limited to package and derivation objects: @dfn{compilers} able to ``lower'' other high-level objects to -derivations can be defined, such that these objects can also be inserted +derivations or files in the store can be defined, +such that these objects can also be inserted into gexps. For example, a useful type of high-level object that can be inserted in a gexp is ``file-like objects'', which make it easy to add files to the store and refer to them in @@ -3400,6 +3402,20 @@ also modules containing build tools. To make it clear that they are meant to be used in the build stratum, these modules are kept in the @code{(guix build @dots{})} name space. +@cindex lowering, of high-level objects in gexps +Internally, high-level objects are @dfn{lowered}, using their compiler, +to either derivations or store items. For instance, lowering a package +yields a derivation, and lowering a @code{plain-file} yields a store +item. This is achieved using the @code{lower-object} monadic procedure. + +@deffn {Monadic Procedure} lower-object @var{obj} [@var{system}] @ + [#:target #f] +Return as a value in @var{%store-monad} the derivation or store item +corresponding to @var{obj} for @var{system}, cross-compiling for +@var{target} if @var{target} is true. @var{obj} must be an object that +has an associated gexp compiler, such as a @code{<package>}. +@end deffn + @c ********************************************************************* @node Utilities |