Bulat Ziganshin wrote:
• The syntax gains very little over the nice consistent syntax we already have – all you do is move a symbol a little to the left.
action x y >>= \v -> do action x y $ \v -> do
One way to settle this kind of dispute would be a real macro system. Bulat could define and use the desired syntax without modifying the language definition in a way that would disturb others. Template Haskell is great for some things, but it's unsuitable and unsatisfying in a case like this. This is out of scope for Haskell', of course, but it's something the community should consider adding at some point. I've uploaded a package called preprocessor-tools[1] to Hackage that provides very quick-and-dirty syntax extension using a preprocessor. I used it to define a do-notation for parameterized monads, back before GHC supported that. At one point I used it to define syntax for a "continuation let", which binds the "result" of a CPS-style function [2]: clet P = E1 in E === E1 (\P -> E) I think this is what Bulat wants. (Bulat, if you want to try this, let me know and I'll try to resurrect the code.) Cheers, Jesse [1] http://hackage.haskell.org/cgi-bin/hackage-scripts/package/preprocessor-tool... [2] It seems to generalize nicely: clet P1 = E1 ... Pn = En in E === E1 (\P1 -> ... -> En (\Pn -> E) ... ) === flip runCont id $ do P1 <- Cont E1 ... Pn <- Cont En return E