Allow applying type to label
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE TypeApplications #-}
{-# LANGUAGE OverloadedLabels #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE DataKinds #-}
import GHC.TypeLits
import GHC.OverloadedLabels
instance IsLabel "answer" Int where
fromLabel _ = 42
answer :: IsLabel "answer" a => a
answer = #answer
The follow works:
>>> answer @Int
42
but fails with a label:
>>> #answer @Int
<interactive>:...:1: error:
• Cannot not apply expression of type ‘t0’
to a visible type argument ‘Int’
• In the expression: #answer @Int
In an equation for ‘it’: it = #answer @Int
Trac metadata
| Trac field | Value |
|---|---|
| Version | 7.10.3 |
| Type | FeatureRequest |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | Compiler |
| Test case | |
| Differential revisions | |
| BlockedBy | |
| Related | |
| Blocking | |
| CC | |
| Operating system | |
| Architecture |