ScopeConflict Error

Example

module ScopeConflict where

-- `Prelude` exports a function called `id`
import Prelude

identity :: Number
identity = 1

Cause

The ScopeConflict error occurs when an attempt is made to define a value or other name when the same name is already in scope.

Fix

• Hide the problematic imports with a hiding list:

  purescriptCopy

  module NoScopeConflict where
  
  import Prelude hiding (identity)
  
  identity :: Number
  identity = 1
  

• Alternatively, import the conflicting module using the as keyword:

  purescriptCopy

  module NoScopeConflict where
  
  import Prelude as P
  
  identity :: Number
  identity = 1
  

Notes

A common case this arises at the moment is if PureScript 0.11.x libraries are used with the 0.10.x compiler. The resulting error is:

Conflicting definitions are in scope for kind Effect from the following modules:

    Control.Monad.Eff
    Prim

To fix this either downgrade the libraries, or upgrade the compiler.