base should export Typeable instances of its promoted data constructors
As initially reported in #8486 (closed), base
does not export Typeable
instances for its promoted data constructors, as witnessed by this:
{-# LANGUAGE DataKinds #-}
import Data.Typeable
x = typeRep (Proxy :: Proxy True)
yields
No instance for (Typeable 'True) arising from a use of ‘typeRep’
In the expression: typeRep (Proxy :: Proxy True)
In an equation for ‘x’: x = typeRep (Proxy :: Proxy True)
It is indeed possible to derive these instances locally with standalone deriving, but that seems very problematic, should multiple modules do that independently.
Trac metadata
Trac field | Value |
---|---|
Version | 7.8.2 |
Type | FeatureRequest |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |