#10963: Beginner-targeted language extension -------------------------------------+------------------------------------- Reporter: kanetw | Owner: Type: feature request | Status: patch Priority: normal | Milestone: Component: Compiler | Version: 7.10.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D2136 Wiki Page: | -------------------------------------+------------------------------------- Comment (by kanetw): Replying to [comment:7 takenobu]:
Hi,
Is Alexander Kjeldaas's representation idea useful? [1]
[1] https://mail.haskell.org/pipermail/ghc- devs/2016-February/011398.html
{{{ Prelude> :t foldr foldr :: Foldable t => (a -> b -> b) -> b -> t a -> b For example: foldr :: (a -> b -> b) -> b -> [a] -> b foldr :: (a -> b -> b) -> b -> Maybe a -> b foldr :: (a -> b -> b) -> b -> Identity a -> b foldr :: (a -> b -> b) -> b -> (c, a) -> b and more }}}
I like this, but this is also kinda difficult. When I was planning on implementing this I ran into the problem that we have a very rapidly growing number of example specializations, and it's hard to decide which ones should be shown and which ones shouldn't. See also some of the discussion [https://ghc.haskell.org/trac/ghc/ticket/10972 here] and [https://mail.haskell.org/pipermail/haskell-cafe/2015-October/121835.html here]. I'm not sure whether I'd prefer this to be under :t, :i, or separate. :t right now is nicely copy-pastable and adding more info would impact that. :i can't evaluate expressions so it'd have to be overloaded. Having it separate makes it less obvious for beginners who might be using old course material that doesn't know of :<fancy new command>. I think having it in :t would be the least worst option assuming people who write stuff that uses GHCi programatically agree. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10963#comment:10 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler