monads: Add 'interned-file'.

* guix/monads.scm (interned-file): New procedure.
* tests/monads.scm ("interned-file"): New test.
* doc/guix.texi (The Store Monad): Document it.

1 files changed, 13 insertions, 0 deletions

diff --git a/guix/monads.scm b/guix/monads.scm
index c2c6f1a03d..4af2b704ab 100644
--- a/guix/monads.scm
+++ b/guix/monads.scm
@@ -55,6 +55,7 @@
             run-with-store
             text-file
             text-file*
+            interned-file
             package-file
             origin->derivation
             package->derivation
@@ -362,6 +363,18 @@ and store file names; the resulting store file holds references to all these."
     (derivation-expression name (builder inputs)
                            #:inputs inputs)))
 
+(define* (interned-file file #:optional name
+                        #:key (recursive? #t))
+  "Return the name of FILE once interned in the store.  Use NAME as its store
+name, or the basename of FILE if NAME is omitted.
+
+When RECURSIVE? is true, the contents of FILE are added recursively; if FILE
+designates a flat file and RECURSIVE? is true, its contents are added, and its
+permission bits are kept."
+  (lambda (store)
+    (add-to-store store (or name (basename file))
+                  recursive? "sha256" file)))
+
 (define* (package-file package
                        #:optional file
                        #:key (system (%current-system)) (output "out"))