Haskell-DeriveGeneric杂注未被识别
我的Haskell文件顶部有以下内容:Haskell-DeriveGeneric杂注未被识别,haskell,pragma,Haskell,Pragma,我的Haskell文件顶部有以下内容: {-# LANGUAGE DeriveGeneric, OverloadedStrings, DefaultSignatures, TypeOperators, FlexibleContexts, RecordWildCards, FlexibleInstances, ExtendedDefaultRules #-} module Main where import qualified Data.Map as Map import qualif
{-# LANGUAGE DeriveGeneric, OverloadedStrings, DefaultSignatures, TypeOperators, FlexibleContexts, RecordWildCards, FlexibleInstances, ExtendedDefaultRules #-}
module Main where
import qualified Data.Map as Map
import qualified Data.Set as Set
import Data.Text (Text)
import Data.DateTime
import Data.Aeson
newtype Price = Price Float deriving Generic
但是,当我跑步时:
$ stack ghci
...
Prelude> :l myfile.hs
[1 of 1] Compiling Main ( myfile.hs, interpreted )
myfile.hs:13:38: error:
Not in scope: type constructor or class ‘Generic’
|
13 | newtype Price = Price Float deriving Generic
| ^^^^^^^
Failed, no modules loaded.
它似乎不接受我对泛型的pragma。我做错了什么?现在看来,这似乎应该是可行的。您还需要导入
GHC.Generics
:
-- other imports
import GHC.Generics
-- more imports