This proposal contains various procedures that return procedures as well as a few others, drawn from an earlier version of Chicken. Common Lisp has a few of them too.
The documentation style, rather than showing only how the procedures are invoked, also shows how the returned procedures would be invoked. This is done in order to make the descriptions easier to understand.
((constantly obj ...) arg ...)
Returns the obj objects as its values, ignoring args.
((complement proc) obj)
Returns #t when (''proc obj'') returns #f, and #f` otherwise.
((compose proc ... ) arg ...)
Passes the args to the first proc, which returns any number of values. These are then passed to the next proc, and so on until the final proc is reached. If there are no procs, returns its arguments as values.
((simple-compose proc ...) arg)
Passes arg to the first proc, which returns one value. This is then passed to the next proc, and so on until the final proc is reached. If there are no procs, returns its argument.
((conjoin predicate ...) arg ...)
Returns #t if the args satisfy all the predicates, and #f otherwise.
((disjoin predicate ...) arg ...)
Returns #t if the args satisfy any of the predicates.
((each proc ... ) arg ...)
Applies each of the procs in turn to args, discarding the results and returning an unspecified value.
((flip proc) arg1 arg2)
Returns (proc arg2 arg1).
((all-of? predicate)
Applies predicate to each element of list in turn, and immediately returns #f if predicate is not satisfied by that element; otherwise returns #t.
((any-of? predicate) list)
Applies predicate to each element of list in turn, and immediately returns #t if predicate is satisfied by that element; otherwise returns #f.
((map-reduce mapper reducer) list)
Returns `(apply ''reducer'' (''mapper list''))`.
(always obj)
Ignores its arguments and always returns #t.
(never obj)
Ignores its arguments and always returns #f.
(identity obj)
Returns obj.