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Module Import

import syntax​

Take an Example:

module Shapes
where

import Data.Number (pi)
import Data.Ord (abs)

data Shape = Circle Number Number Number
           | Rectangle Number Number Number Number

surface :: Shape -> Number
surface (Circle _ _ r) = pi * r * r
surface (Rectangle x1 y1 x2 y2) = (abs $ x2 - x1) * (abs $ y2 - y1)

import all (implicitly)​

The following will import all of the values and types in module A:

module App where
import Shapes

import explicitly​

Values, operators (wrapped in parentheses), type constructors, data constructors, and type classes can all be explicitly imported.

A type constructor can be followed by a list of associated data constructors to import in parentheses.

import Shapes (Shape(Circle))
note

For 'import', we can partially import value constructors; but this does not work for export!

A double dot (..) can be used to import all data constructors for a given type constructor:

  import Shapes (Shape(..))

reference doc​

Language reference-module