gexp: 'gexp->script' and 'gexp->file' have a new #:module-path parameter.

* guix/gexp.scm (load-path-expression): Add 'path' optional parameter.
(gexp->script): Add #:module-path and honor it.
(gexp->file): Likewise.
* tests/gexp.scm ("gexp->script #:module-path"): New test.
* doc/guix.texi (G-Expressions): Update accordingly.

1 files changed, 23 insertions, 12 deletions

diff --git a/guix/gexp.scm b/guix/gexp.scm
index 8dea022e04..4a2e5a682e 100644
--- a/guix/gexp.scm
+++ b/guix/gexp.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2014, 2015, 2016, 2017 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2014, 2015, 2016, 2017, 2018 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2018 Clément Lassieur <clement@lassieur.org>
 ;;;
 ;;; This file is part of GNU Guix.
@@ -1116,11 +1116,14 @@ they can refer to each other."
   (module-ref (resolve-interface '(gnu packages guile))
               'guile-2.2))
 
-(define (load-path-expression modules)
+(define* (load-path-expression modules #:optional (path %load-path))
   "Return as a monadic value a gexp that sets '%load-path' and
-'%load-compiled-path' to point to MODULES, a list of module names."
-  (mlet %store-monad ((modules  (imported-modules modules))
-                      (compiled (compiled-modules modules)))
+'%load-compiled-path' to point to MODULES, a list of module names.  MODULES
+are searched for in PATH."
+  (mlet %store-monad ((modules  (imported-modules modules
+                                                  #:module-path path))
+                      (compiled (compiled-modules modules
+                                                  #:module-path path)))
     (return (gexp (eval-when (expand load eval)
                     (set! %load-path
                       (cons (ungexp modules) %load-path))
@@ -1129,11 +1132,13 @@ they can refer to each other."
                             %load-compiled-path)))))))
 
 (define* (gexp->script name exp
-                       #:key (guile (default-guile)))
+                       #:key (guile (default-guile))
+                       (module-path %load-path))
   "Return an executable script NAME that runs EXP using GUILE, with EXP's
-imported modules in its search path."
+imported modules in its search path.  Look up EXP's modules in MODULE-PATH."
   (mlet %store-monad ((set-load-path
-                       (load-path-expression (gexp-modules exp))))
+                       (load-path-expression (gexp-modules exp)
+                                             module-path)))
     (gexp->derivation name
                       (gexp
                        (call-with-output-file (ungexp output)
@@ -1148,12 +1153,16 @@ imported modules in its search path."
 
                            (write '(ungexp set-load-path) port)
                            (write '(ungexp exp) port)
-                           (chmod port #o555)))))))
+                           (chmod port #o555))))
+                      #:module-path module-path)))
 
-(define* (gexp->file name exp #:key (set-load-path? #t))
+(define* (gexp->file name exp #:key
+                     (set-load-path? #t)
+                     (module-path %load-path))
   "Return a derivation that builds a file NAME containing EXP.  When
 SET-LOAD-PATH? is true, emit code in the resulting file to set '%load-path'
-and '%load-compiled-path' to honor EXP's imported modules."
+and '%load-compiled-path' to honor EXP's imported modules.  Lookup EXP's
+modules in MODULE-PATH."
   (match (if set-load-path? (gexp-modules exp) '())
     (()                                           ;zero modules
      (gexp->derivation name
@@ -1164,13 +1173,15 @@ and '%load-compiled-path' to honor EXP's imported modules."
                        #:local-build? #t
                        #:substitutable? #f))
     ((modules ...)
-     (mlet %store-monad ((set-load-path (load-path-expression modules)))
+     (mlet %store-monad ((set-load-path (load-path-expression modules
+                                                              module-path)))
        (gexp->derivation name
                          (gexp
                           (call-with-output-file (ungexp output)
                             (lambda (port)
                               (write '(ungexp set-load-path) port)
                               (write '(ungexp exp) port))))
+                         #:module-path module-path
                          #:local-build? #t
                          #:substitutable? #f)))))