Type application without space [GHC-84077]

Language extension: TypeApplications

Type application syntax requires a space before @. This is described in the documentation of the visible type application feature.

Examples

Missing space before type application

There is no space before the type application @Int.

Error Message

MissingSpaceTypeOperator.hs:6:7: error:
    @-pattern in expression context: x@Int
    Type application syntax requires a space before '@'
  |
6 | f x = x@Int
  |       ^^^^^

MissingSpaceTypeApplication.hs

Before

{-# LANGUAGE TypeApplications #-}

 module MissingSpaceTypeApplication where

 f :: (forall a. a -> b) -> (Int -> b)
 f x = x@Int

After

{-# LANGUAGE TypeApplications #-}

 module MissingSpaceTypeApplication where

 f :: (forall a. a -> b) -> (Int -> b)
 f x = x @Int

Missing space in type application

Error Message

Example.hs:7:5: error:
    @-pattern in expression context: g@Int
    Type application syntax requires a space before '@'
  |
7 | f = g@Int
  |     ^^^^^

Explanation

A space is missing before the type application. The expression cannot be correctly parsed.

Example.hs

Before

{-# LANGUAGE TypeApplications #-}
module Example where

g :: (Num a) => a -> a
g x = x * 2

f = g@Int

After

{-# LANGUAGE TypeApplications #-}
module Example where

g :: (Num a) => a -> a
g x = x * 2

f = g @Int