Infix ($) is so noisy that I’ve adapted a code style that replaces it entirely with parentheses. And the hack to make ($) work with higher-rank types is pretty awkward too. Seen from these angles, I’m very much in favour of ArgumentDo. However, the clarity of `runST do ...` comes at a high price: only some of the missing ($) make the code clearer, where others make it much worse. You give a couple of examples yourself:
f do x do y
I have to think a bit how this might be parsed even after reading the proposal. I’m a bit torn on whether I like or not like it, but I think the ArgumentDo syntax that I find awkward now is a matter of style, and one could probably get used to only using it in certain places, despite all of the possibilities. David/quchen