maplist-expander

Rationale

In Prolog, maplist is a great predicate that I try to use whenever applicable. Yet, there are two issues I identified:

• At least in SICStus Prolog, maplist is slowed compared to writing the loop manually. When preparing benchmarks that uses maplist with an identity function, I observed 10-20x speed-ups when calling the loop instead.
• There are only so many arities of maplist that are implemented (usually maplist/2 to maplist/4 - if, say, maplist/6 is needed, one has to write it oneself).

However, I still like using maplist. Using term expansion, an explicit recursion can be generated instead. This keeps the nice, clean looks of using maplist, yet gives us the performance and allows us to stop worrying about limited arities.

Usage

• Drop maplist_expander.pl into your project.
• Include the term expander by adding :- use_module(maplist_expander). to the top of your module.

Then, you're all set!

Limitations

• Currently, this only works for SICStus Prolog. I might add a term expander for SWI Prolog in the future.
• No expansion happens in combination with other meta-predicates (e.g., call).
• It is not well-tested yet, so I hope you like experiments :-)