Duck util-list.

doc/d-utils.md

@@ -256,3 +256,21 @@ When the ```line``` contains whitespace character(s), it returns a
 pair consisting of symbol created by interning the string of
 non-whitespace characters before the first whitespace character and
 the string with the rest of the line.
+
+## util-list [module]
+
+    (import util-list)
+
+This module implements basic list functionality which is common in
+most scheme implementations.
+
+### filter [procedure]
+
+    (filter pred?
+            lst)
+
+* ```pred?``` - procedure accepting any value and returning #t or #f
+* ```lst``` - list to be filtered
+
+Returns a list containing only elements matching given ```pred?```
+predicate.