#15546: Display coaxiom branch incompatibilities in GHCi -------------------------------------+------------------------------------- Reporter: mniip | Owner: (none) Type: feature | Status: new request | Priority: normal | Milestone: 8.6.1 Component: GHCi | Version: 8.4.3 Keywords: TypeFamilies, | Operating System: Unknown/Multiple GHCi | Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Currently the only way to figure out how GHC figured out compatibility of branches in a closed type family is to compile it to `.hi` and then sieve through `--show-iface` output. Something as simple this should suffice: {{{#!hs
:i == type family (==) (a :: k) (b :: k) :: Bool where (==) (f a) (g b) = (f == g) && (a == b) (==) a a = 'True -- incompatible with: 0 (==) _1 _2 = 'False -- incompatible with: 0, 1 -- Defined in ‘Data.Type.Equality’ infix 4 == }}}
-- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15546 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler