Unable to instantiate data members of kind Nat in backpack signatures.
This is in context with backpack signatures and their instantiation with concrete implementation. Consider the signature Abstract
which contains a
data NatType
of kind Nat
.
{- skipped relevant language extensions -}
signature Abstract where
import GHC.TypeLits
data NatType :: Nat -- comment this out
Concrete implementations are unable to instantiate this abstract class during linking
module Concrete where
type NatType = 42
This is neither working with explicit .bkp files nor actual cabal package. I have isolated a minimum example into a repository a cabal packages as well as a single bkp file. The urls above also have the associated ghc log messages.
The version of ghc I have tested with is 8.4.1
Trac metadata
Trac field | Value |
---|---|
Version | 8.4.1 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |