It's the caller's job to instantiate a generic function only with types that succeed at runtime when the constraint's operations are called.

• ghc

  95 2,971 9.7 Haskell

  Mirror of the Glasgow Haskell Compiler. Please submit issues and patches to GHC's Gitlab instance (https://gitlab.haskell.org/ghc/ghc). First time contributors are encouraged to get started with the newcomers info (https://gitlab.haskell.org/ghc/ghc/wikis/contributing).

  

i9% ghci GHCi, version 9.0.1: https://www.haskell.org/ghc/ :? for help ghci> import qualified Data.Map as M ghci> :t M.insert M.insert :: Ord k => k -> a -> M.Map k a -> M.Map k a ghci> :t M.insert (id :: Bool -> Bool) "good luck trying" :1:1: error: • No instance for (Ord (Bool -> Bool)) arising from a use of ‘M.insert’ (maybe you haven't applied a function to enough arguments?) • In the expression: M.insert (id :: Bool -> Bool) "good luck trying" ghci> :t M.insert (id :: Bool -> Bool) "good luck trying" M.empty :1:1: error: • No instance for (Ord (Bool -> Bool)) arising from a use of ‘M.insert’ (maybe you haven't applied a function to enough arguments?) • In the expression: M.insert (id :: Bool -> Bool) "good luck trying" M.empty ghci>

• InfluxDB

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