HasFromInt.purs

module Neon.Class.HasFromInt where

import Data.Enum as Enum
import Neon.Data as Data

-- | Represents types that can be converted from integers. This is typically
-- | used for enumerations.
-- |
-- | ``` purescript
-- | fromInt 1 :: Maybe Bool -- Just true
-- | fromInt 2 :: Maybe Bool -- Nothing
-- | ```
class HasFromInt a where
  fromInt :: Int -> Data.Maybe a

instance booleanHasFromInt :: HasFromInt Boolean where
  fromInt x = Enum.toEnum x

instance charHasFromInt :: HasFromInt Char where
  fromInt x = Enum.toEnum x

instance intHasFromInt :: HasFromInt Int where
  fromInt x = Data.Just x

instance orderingHasFromInt :: HasFromInt Data.Ordering where
  fromInt x = case x of
    0 -> Data.Just Data.LT
    1 -> Data.Just Data.EQ
    2 -> Data.Just Data.GT
    _ -> Data.Nothing