You can probably implement Elm in PureScript pretty trivially, AFAICT. AFAIK Elm doesn't have any static guarantees about lack-of-space leaks or lack-of-time leaks. Or, maybe it just lacks higher-order-signals? (Which would mostly prevent those sorts of things happening). I found Neel Krishnaswami's papers on a static way to decide/prevent these things statically very interesting. I haven't found any implementation of his ideas, but they seem pretty solid: http://www.cs.bham.ac.uk/~krishnan/