Hi Edward, I read your slides a few weeks ago when they were posted on Reddit and found your approach very interesting. In fact it provided the inspiration for the parser I've written. I did not use the same strategy, however, because parsing makefiles poses its own challenges. The make syntax is actually the union of two different languages, one for defining targets and one for commands. It's easy to identify commands following target definitions (they belong to lines starting with a tab), but if you jump to the middle of a makefile you can't decide, for example, if you are inside a define block (that should be parsed like a command) because the lines in its body are not marked by any specific prefix. Thus the need for a sequential scan. All this may seem rather involved and specific to an unusual format, but one encounters the same problem when parsing here-documents in shell scripts or multi line (triple-quoted) comments in Python. The cache trashing effect you mention is certainly an issue I did not foresee. I guess a possible solution would be to base parMap on different 'par' primitive; one that sparks a number of computations equal to the number of available OS threads and then blocks until at least one of them is done. -- AB