4 files changed, 24 insertions(+), 2 deletions(-)

M doc/guix.texi
M guix/scripts/build.scm
M guix/ui.scm
M tests/guix-build.sh

@@ 2244,7 2244,11 @@ (gnu packages guile)
 guile-1.8)}, which unambiguously designates this specific variant of
 version 1.8 of Guile.
 
-Alternately, @var{expr} may refer to a zero-argument monadic procedure
+Alternately, @var{expr} may be a G-expression, in which case it is used
+as a build program passed to @code{gexp->derivation}
+(@pxref{G-Expressions}).
+
+Lastly, @var{expr} may refer to a zero-argument monadic procedure
 (@pxref{The Store Monad}).  The procedure must return a derivation as a
 monadic value, which is then passed through @code{run-with-store}.
 

@@ 24,6 24,7 @@
   #:use-module (guix packages)
   #:use-module (guix utils)
   #:use-module (guix monads)
+  #:use-module (guix gexp)
   #:use-module (ice-9 format)
   #:use-module (ice-9 match)
   #:use-module (ice-9 vlist)


@@ 338,6 339,11 @@ packages."
             `(argument . ,p))
            ((? procedure? proc)
             (let ((drv (run-with-store store (proc) #:system system)))
+              `(argument . ,drv)))
+           ((? gexp? gexp)
+            (let ((drv (run-with-store store
+                         (gexp->derivation "gexp" gexp
+                                           #:system system))))
               `(argument . ,drv)))))
         (opt opt))
        opts))

@@ 238,6 238,14 @@ interpreted."
         (leave (_ "~a: ~a~%") proc
                (apply format #f format-string format-args))))))
 
+(define %guix-user-module
+  ;; Module in which user expressions are evaluated.
+  (let ((module (make-module)))
+    (beautify-user-module! module)
+    ;; Use (guix gexp) so that one can use #~ & co.
+    (module-use! module (resolve-interface '(guix gexp)))
+    module))
+
 (define (read/eval str)
   "Read and evaluate STR, raising an error if something goes wrong."
   (let ((exp (catch #t


@@ 248,7 256,7 @@ interpreted."
                         str args)))))
     (catch #t
       (lambda ()
-        (eval exp the-root-module))
+        (eval exp %guix-user-module))
       (lambda args
         (leave (_ "failed to evaluate expression `~a': ~s~%")
                exp args)))))

@@ 80,3 80,7 @@ guix build -e "(begin
                    (gexp->derivation \"test\"
                                      (gexp (mkdir (ungexp output))))))" \
    --dry-run
+
+# Running a gexp.
+guix build -e '#~(mkdir #$output)' -d
+guix build -e '#~(mkdir #$output)' -d | grep 'gexp\.drv'