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Add Fail instance for Bind ZipList #73

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Merged
merged 2 commits into from
Jun 11, 2016
Merged

Add Fail instance for Bind ZipList #73

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24c73fa
Add `Fail` instance for `Bind ZipList`
joneshf Jun 8, 2016
376628c
Add alternatives and use `unsafeCrashWith`
joneshf Jun 10, 2016
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14 changes: 12 additions & 2 deletions src/Data/List/ZipList.purs
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Original file line number Diff line number Diff line change
Expand Up @@ -7,15 +7,14 @@ module Data.List.ZipList
) where

import Prelude

import Control.Alt (class Alt)
import Control.Alternative (class Alternative)
import Control.Plus (class Plus)

import Data.Foldable (class Foldable, foldMap, foldl, foldr)
import Data.List.Lazy (List, repeat, zipWith)
import Data.Monoid (class Monoid, mempty)
import Data.Traversable (class Traversable, traverse, sequence)
import Partial.Unsafe (unsafeCrashWith)

-- | `ZipList` is a newtype around `List` which provides a zippy
-- | `Applicative` instance.
Expand Down Expand Up @@ -65,3 +64,14 @@ instance plusZipList :: Plus ZipList where
empty = mempty

instance alternativeZipList :: Alternative ZipList

instance zipListIsNotBind
:: Fail """
ZipList is not Bind. Any implementation would break the associativity law.

Possible alternatives:
Data.List.List
Data.List.Lazy.List
"""
=> Bind ZipList where
bind = unsafeCrashWith "bind: unreachable"