Display coaxiom branch incompatibilities in GHCi
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:
> :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 ==
Trac metadata
Trac field | Value |
---|---|
Version | 8.4.3 |
Type | FeatureRequest |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | GHCi |
Test case | |
Differential revisions | |
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Blocking | |
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