add op*

2 files changed, 27 insertions, 0 deletions

diff --git a/mew.scm b/mew.scm
index 70edbdd..7d9d2ac 100644
--- a/mew.scm
+++ b/mew.scm
@@ -23,6 +23,7 @@
      <>?
      ~?)
 
+  (import-for-syntax srfi-1)
   (import-for-syntax matchable)
 
   (import scheme
@@ -172,6 +173,20 @@
           ((_ x) `(,(rename 'lambda) ... ,x))
           ((_ . rest) `(,(rename 'lambda) (_) ,rest))))))
 
+  (define-syntax op*
+    (er-macro-transformer
+     (lambda (expr rename compare)
+       (when (= 1 (length expr))
+         (syntax-error "op* needs at least one argument"))
+       `(,(rename 'lambda) ...
+         ,(receive (pre post) (break (lambda (x) (compare '... x)) (cdr expr))
+            (match post
+              (()      `(,(rename apply) ,@pre ...))
+              ((x)     `(,(rename apply) ,@pre ...))
+              ((x . y) `(,(rename apply) ,@pre
+                         (,(rename append) ... (,(rename list) ,@y))))
+              ))))))
+
   (define-syntax rep
     (syntax-rules ()
       ((_ name ((var val) ...) body ...)
diff --git a/mew.svnwiki b/mew.svnwiki
index 49831a9..c3c03c7 100644
--- a/mew.svnwiki
+++ b/mew.svnwiki
@@ -117,6 +117,18 @@ If {{<form>>} is empty, behaves as {{values}}, i.e. the identity function.
 
 {{(op + 2 _)}} is the function that adds 2 to its argument.
 
+<syntax>(op* <form>)</syntax>
+
+Returns a procedure that evaluates {{<form>}} with {{...}} expanded
+to all its arguments.  {{...}} must only appear once and must not
+be nested further.  If {{...} does not appear in {{<form>}}, it's
+added implicitly at the end.
+
+{{(op* + 5)}} is the function that adds 5 and then all its arguments.
+
+{{(op* - 0 ... 2)}} is the function that subtracts all its arguments from 0
+and finally 2.
+
 <procedure>(negate <fun>)</procedure>
 
 Alias for {{complement}}.