Comments (2)
phadej
commented on June 2, 2024
The issue is reproducible only with GHC-8.0 and GHC-8.2
With
{-# LANGUAGE DeriveGeneric #-}
{-# LANGUAGE TypeApplications #-}
import Prelude
import GHC.Generics
import Control.Lens
import Data.Generics.Product
data Foo = Foo { name :: String } deriving (Show, Generic)
test1 :: Foo -> String
test1 foo = foo ^. field @"name"
test2 :: Foo -> Int
test2 bar = bar ^. field @"name"GHC-8.4.4
[1 of 1] Compiling Main ( lleak.hs, interpreted )
lleak.hs:15:20: error:
• Couldn't match type ‘[Char]’ with ‘Int’
arising from a use of ‘field’
• In the second argument of ‘(^.)’, namely ‘field @"name"’
In the expression: bar ^. field @"name"
In an equation for ‘test2’: test2 bar = bar ^. field @"name"
|
15 | test2 bar = bar ^. field @"name"
| ^^^^^^^^^^^^^
GHC-8.0.2
[1 of 1] Compiling Main ( lleak.hs, interpreted )
lleak.hs:12:20: error:
• Couldn't match type ‘Int’ with ‘[Char]’
arising from a functional dependency between constraints:
‘generic-lens-1.1.0.0:Data.Generics.Product.Internal.GLens.GLens
(Data.Generics.Product.Fields.HasTotalFieldPSym "name")
(K1 R String)
(K1 R String)
[Char]
[Char]’
arising from a use of ‘field’ at lleak.hs:12:20-32
‘generic-lens-1.1.0.0:Data.Generics.Product.Internal.GLens.GLens
(Data.Generics.Product.Fields.HasTotalFieldPSym "name")
(K1 R String)
(K1 R String)
Int
Int’
arising from a use of ‘field’ at lleak.hs:15:20-32
• In the second argument of ‘(^.)’, namely ‘field @"name"’
In the expression: foo ^. field @"name"
In an equation for ‘test1’: test1 foo = foo ^. field @"name"
lleak.hs:15:20: error:
• Couldn't match type ‘[Char]’ with ‘Int’
arising from a use of ‘field’
• In the second argument of ‘(^.)’, namely ‘field @"name"’
In the expression: bar ^. field @"name"
In an equation for ‘test2’: test2 bar = bar ^. field @"name"
Failed, modules loaded: none.
GHC-8.2.2
[1 of 1] Compiling Main ( lleak.hs, interpreted )
lleak.hs:12:20: error:
• Couldn't match type ‘Int’ with ‘[Char]’
arising from a functional dependency between constraints:
‘generic-lens-1.1.0.0:Data.Generics.Product.Internal.GLens.GLens
(Data.Generics.Product.Fields.HasTotalFieldPSym "name")
(K1 R String)
(K1 R String)
[Char]
[Char]’
arising from a use of ‘field’ at lleak.hs:12:20-32
‘generic-lens-1.1.0.0:Data.Generics.Product.Internal.GLens.GLens
(Data.Generics.Product.Fields.HasTotalFieldPSym "name")
(K1 R String)
(K1 R String)
Int
Int’
arising from a use of ‘field’ at lleak.hs:15:20-32
• In the second argument of ‘(^.)’, namely ‘field @"name"’
In the expression: foo ^. field @"name"
In an equation for ‘test1’: test1 foo = foo ^. field @"name"
|
12 | test1 foo = foo ^. field @"name"
| ^^^^^^^^^^^^^
lleak.hs:15:20: error:
• Couldn't match type ‘[Char]’ with ‘Int’
arising from a use of ‘field’
• In the second argument of ‘(^.)’, namely ‘field @"name"’
In the expression: bar ^. field @"name"
In an equation for ‘test2’: test2 bar = bar ^. field @"name"
|
15 | test2 bar = bar ^. field @"name"
| ^^^^^^^^^^^^^
Failed, no modules loaded.
GHC-8.6.2
[1 of 1] Compiling Main ( lleak.hs, interpreted )
lleak.hs:15:20: error:
• Couldn't match type ‘[Char]’ with ‘Int’
arising from a use of ‘field’
• In the second argument of ‘(^.)’, namely ‘field @"name"’
In the expression: bar ^. field @"name"
In an equation for ‘test2’: test2 bar = bar ^. field @"name"
|
15 | test2 bar = bar ^. field @"name"
| ^^^^^^^^^^^^^
Failed, no modules loaded.
from generic-lens.
oliver-batchelor
commented on June 2, 2024
Ah, thanks! I knew I had forgotten some details. Good to know it is
essentially solved, I'll look to update ghc just to get around this one!
…On Mon, Dec 10, 2018 at 3:38 PM Oleg Grenrus ***@***.***> wrote:
The issue is reproducible only with GHC-8.0 and GHC-8.2
------------------------------
With
{-# LANGUAGE DeriveGeneric #-}
{-# LANGUAGE TypeApplications #-}
import Prelude
import GHC.Generics
import Control.Lens
import Data.Generics.Product
data Foo = Foo { name :: String } deriving (Show, Generic)
test1 :: Foo -> String
test1 foo = foo ^. field @"name"
test2 :: Foo -> Int
test2 bar = bar ^. field @"name"
GHC-8.4.4
[1 of 1] Compiling Main ( lleak.hs, interpreted )
lleak.hs:15:20: error:
• Couldn't match type ‘[Char]’ with ‘Int’
arising from a use of ‘field’
• In the second argument of ‘(^.)’, namely ‘field @"name"’
In the expression: bar ^. field @"name"
In an equation for ‘test2’: test2 bar = bar ^. field @"name"
|
15 | test2 bar = bar ^. field @"name"
| ^^^^^^^^^^^^^
GHC-8.0.2
[1 of 1] Compiling Main ( lleak.hs, interpreted )
lleak.hs:12:20: error:
• Couldn't match type ‘Int’ with ‘[Char]’
arising from a functional dependency between constraints:
‘generic-lens-1.1.0.0:Data.Generics.Product.Internal.GLens.GLens
(Data.Generics.Product.Fields.HasTotalFieldPSym "name")
(K1 R String)
(K1 R String)
[Char]
[Char]’
arising from a use of ‘field’ at lleak.hs:12:20-32
‘generic-lens-1.1.0.0:Data.Generics.Product.Internal.GLens.GLens
(Data.Generics.Product.Fields.HasTotalFieldPSym "name")
(K1 R String)
(K1 R String)
Int
Int’
arising from a use of ‘field’ at lleak.hs:15:20-32
• In the second argument of ‘(^.)’, namely ‘field @"name"’
In the expression: foo ^. field @"name"
In an equation for ‘test1’: test1 foo = foo ^. field @"name"
lleak.hs:15:20: error:
• Couldn't match type ‘[Char]’ with ‘Int’
arising from a use of ‘field’
• In the second argument of ‘(^.)’, namely ‘field @"name"’
In the expression: bar ^. field @"name"
In an equation for ‘test2’: test2 bar = bar ^. field @"name"
Failed, modules loaded: none.
GHC-8.2.2
[1 of 1] Compiling Main ( lleak.hs, interpreted )
lleak.hs:12:20: error:
• Couldn't match type ‘Int’ with ‘[Char]’
arising from a functional dependency between constraints:
‘generic-lens-1.1.0.0:Data.Generics.Product.Internal.GLens.GLens
(Data.Generics.Product.Fields.HasTotalFieldPSym "name")
(K1 R String)
(K1 R String)
[Char]
[Char]’
arising from a use of ‘field’ at lleak.hs:12:20-32
‘generic-lens-1.1.0.0:Data.Generics.Product.Internal.GLens.GLens
(Data.Generics.Product.Fields.HasTotalFieldPSym "name")
(K1 R String)
(K1 R String)
Int
Int’
arising from a use of ‘field’ at lleak.hs:15:20-32
• In the second argument of ‘(^.)’, namely ‘field @"name"’
In the expression: foo ^. field @"name"
In an equation for ‘test1’: test1 foo = foo ^. field @"name"
|
12 | test1 foo = foo ^. field @"name"
| ^^^^^^^^^^^^^
lleak.hs:15:20: error:
• Couldn't match type ‘[Char]’ with ‘Int’
arising from a use of ‘field’
• In the second argument of ‘(^.)’, namely ‘field @"name"’
In the expression: bar ^. field @"name"
In an equation for ‘test2’: test2 bar = bar ^. field @"name"
|
15 | test2 bar = bar ^. field @"name"
| ^^^^^^^^^^^^^
Failed, no modules loaded.
GHC-8.6.2
[1 of 1] Compiling Main ( lleak.hs, interpreted )
lleak.hs:15:20: error:
• Couldn't match type ‘[Char]’ with ‘Int’
arising from a use of ‘field’
• In the second argument of ‘(^.)’, namely ‘field @"name"’
In the expression: bar ^. field @"name"
In an equation for ‘test2’: test2 bar = bar ^. field @"name"
|
15 | test2 bar = bar ^. field @"name"
| ^^^^^^^^^^^^^
Failed, no modules loaded.
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- Const and Identity instances for `HasAny` HOT 1
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