#11994: ghci not applying defaulting when showing type -------------------------------------+------------------------------------- Reporter: j.waldmann | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 7.10.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by aavogt): You could (ab)use do notation to get the defaulted type: {{{

:set +t Prelude> x <- return $ 1+1 x :: Integer }}}

The `it` variable is actually generalized, so the reported type is right. After all this works: {{{ Prelude> :set +t Prelude> 1+1 2 it :: Num a => a Prelude> (it :: Int, it :: Double) (2,2.0) it :: (Int, Double) }}} `-XMonoLocalBinds` keeps let from being generalized in files (ie. `let x = 1 in (x::Int,x::Integer)` becomes a type error), so I thought it might make a difference with respect to generalizing `it`. But it has no effect in ghci, not even for the `let x = ...` expression above. At least Richard Eisenberg seems to have said that `MonoLocalBinds` is irrelevant for ghci in a slightly different scenario: <https://mail.haskell.org/pipermail/ghc- devs/2015-August/009636.html>). -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11994#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#11994: ghci not applying defaulting when showing type -------------------------------------+------------------------------------- Reporter: j.waldmann | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 7.10.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by j.waldmann):

if you want defaulting ...

This is not about changing the defaulting rules. It's just about the output of `:set +t`, which looked misleading to me. https://mail.haskell.org/pipermail/ghc-devs/2016-April/011958.html I did not realize that `it` is actually polymorphic. So the output is correct. But then the type of `it` is not the type of the value that is being printed - which is again strange. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11994#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler