An interesting project was kicked around here / proggit the other day, using apltail as the middle of a pipeline transforming APL code into optimized GPU code (Futhark), instead of targeting C. It is a pretty good display of ML's suitability for this sort of task.

I've always been impressed (amazed?) at the performance APL and its descendants get in an interpreted environment -- I'd be interested to see performance comparisons between the output of apl-to-apltail-to-C / apl-to-apltail-to-futhark and an APL interpreter.