Duck util-proc.

doc/d-utils.md

@@ -274,3 +274,69 @@ most scheme implementations.
 
 Returns a list containing only elements matching given ```pred?```
 predicate.
+
+## util-proc [module]
+
+    (import util-proc)
+
+This module provides a few simple procedures for querying properties
+of other procedures.
+
+### improper-list-info [procedure]
+
+    (improper-list-info lst)
+
+Returns two values: the proper part of the list length and #t if
+there is an improper list end
+
+### (procedure-arity=? n) [procedure]
+
+    ((procedure-arity=? proc)
+                        n)
+
+* ```n``` - integer representing the number of arguments
+* ```proc``` - procedure to query
+
+Returns true if the procedure ```proc``` accepts exactly ```n```
+arguments.
+
+### (procedure-arity>=? n) [procedure]
+
+    ((procedure-arity>=? proc)
+                         n)
+
+* ```n``` - integer representing the number of arguments
+* ```proc``` - procedure to query
+
+Returns true if the procedure ```proc``` accepts at least ```n```
+arguments.
+
+### (procedure-arity>? n) [procedure]
+
+    ((procedure-arity>? proc)
+                        n)
+
+* ```n``` - integer representing the number of arguments
+* ```proc``` - procedure to query
+
+Returns true if the procedure ```proc``` accepts more than ```n```
+arguments.
+
+### procedure-num-args [procedure]
+
+    (procedure-num-args proc)
+
+* ```proc``` - procedure to check
+
+Returns the number of mandatory arguments.
+
+### procedure-arg-names [procedure]
+
+    (procedure-arg-names proc)
+
+* ```proc``` - procedure to check
+
+Returns the (possibly improper) list of arguments the procedure
+```proc``` accepts. If it accepts arbitrary number of arguments, it is
+signalled by simple symbol instead of pair at the last position. If it
+accepts an exact number of arguments, it returns a proper list.