Add wrap-maybe to (data optional).

1 files changed, 7 insertions, 1 deletions

diff --git a/data/optional.scm b/data/optional.scm
index 4130bab..7ab944c 100644
--- a/data/optional.scm
+++ b/data/optional.scm
@@ -3,9 +3,10 @@
   #:use-module (ice-9 match)
   #:use-module (control monad)
   #:use-module (data functor)
+  #:use-module (ice-9 curried-definitions)
   #:export (nothing just
                     nothing? just?
-                    from-just
+                    from-just wrap-maybe
                     return-optional)
   #:re-export (>>= >> fmap))
 
@@ -34,6 +35,11 @@ the value embedded in maybe-val"
       (slot-ref maybe-val 'slot)
       default))
 
+(define ((wrap-maybe proc) . values)
+  "Wraps a function in an optional monad, where #f returns are translated to nothing."
+  (let ((v (apply proc values)))
+    (if v (just v) (nothing))))
+
 (define-method (write (this <optional>) port)
   (if (just? this)
       (format port "[Just ~s]" (slot-ref this 'slot))