Add awhen.

1 files changed, 17 insertions, 1 deletions

diff --git a/module/util.scm b/module/util.scm
index 0d4d20d6..0bbab9bc 100644
--- a/module/util.scm
+++ b/module/util.scm
@@ -11,7 +11,7 @@
                 quote?
                 re-export-modules
                 use-modules*
-                -> set aif
+                -> set aif awhen
                 tree-map let-lazy let-env)
   #:replace (let* set! define-syntax
                   when unless if))
@@ -44,6 +44,7 @@
     ((@ (guile) if) p t
      (begin f ...))]))
 
+
 (define-syntax aif
   (lambda (stx)
     (syntax-case stx ()
@@ -51,6 +52,21 @@
        (with-syntax ((it (datum->syntax stx 'it)))
          #'(let ((it condition))
              (if it true-clause false-clause)))])))
+
+(define-syntax awhen
+  (lambda (stx)
+    (syntax-case stx ()
+      [(_ condition body ...)
+       (with-syntax ((it (datum->syntax stx 'it)))
+         #'(let ((it condition))
+             (when it body ...)))])))
+
+#;
+(define-macro (awhen pred . body)
+  `(let ((it ,pred))
+     (when it
+       ,@body)))
+
 
 
 (define-public upstring->symbol (compose string->symbol string-upcase))