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 |