Refactor functors and related packages

This is part of a set of commits that rearrange the dependencies between
multiple packages. The immediate motivation is to allow certain newtypes
to be reused between `profunctor` and `bifunctors`, but this particular
approach goes a little beyond that in two ways: first, it attempts to
move data types (`either`, `tuple`) toward the bottom of the dependency
stack; and second, it tries to ensure no package comes between
`functors` and the packages most closely related to it, in order to open
the possibility of merging those packages together (which may be
desirable if at some point in the future additional newtypes are added
which reveal new and exciting constraints on the module dependency
graph).

Author: rhendric

CHANGELOG.md

@@ -11,6 +11,7 @@ Breaking changes:
 New features:
 - Added `\/` alias for `either` (#51)
 - Added lazy versions of `fromRight` and `fromLeft` (#59)
+- This package no longer depends on the `purescript-bifunctors` and `purescript-foldable-traversable` packages. Relevant instances have been moved to those packages. (TBD)
 
 Bugfixes:
 

bower.json

@@ -16,9 +16,7 @@
     "package.json"
   ],
   "dependencies": {
-    "purescript-bifunctors": "master",
     "purescript-control": "master",
-    "purescript-foldable-traversable": "master",
     "purescript-invariant": "master",
     "purescript-maybe": "master",
     "purescript-prelude": "master"

src/Data/Either.purs

@@ -4,19 +4,11 @@ import Prelude
 
 import Control.Alt (class Alt, (<|>))
 import Control.Extend (class Extend)
-import Data.Bifoldable (class Bifoldable)
-import Data.Bifunctor (class Bifunctor)
-import Data.Bitraversable (class Bitraversable)
 import Data.Eq (class Eq1)
-import Data.Foldable (class Foldable)
-import Data.FoldableWithIndex (class FoldableWithIndex)
 import Data.Functor.Invariant (class Invariant, imapF)
-import Data.FunctorWithIndex (class FunctorWithIndex)
 import Data.Generic.Rep (class Generic)
 import Data.Maybe (Maybe(..), maybe, maybe')
 import Data.Ord (class Ord1)
-import Data.Traversable (class Traversable)
-import Data.TraversableWithIndex (class TraversableWithIndex)
 
 -- | The `Either` type is used to represent a choice between two types of value.
 -- |
@@ -38,18 +30,11 @@ data Either a b = Left a | Right b
 -- | ```
 derive instance functorEither :: Functor (Either a)
 
-instance functorWithIndexEither :: FunctorWithIndex Unit (Either a) where
-  mapWithIndex f = map $ f unit
-
 derive instance genericEither :: Generic (Either a b) _
 
 instance invariantEither :: Invariant (Either a) where
   imap = imapF
 
-instance bifunctorEither :: Bifunctor Either where
-  bimap f _ (Left l) = Left (f l)
-  bimap _ g (Right r) = Right (g r)
-
 -- | The `Apply` instance allows functions contained within a `Right` to
 -- | transform a value contained within a `Right` using the `(<*>)` operator:
 -- |
@@ -209,46 +194,6 @@ instance boundedEither :: (Bounded a, Bounded b) => Bounded (Either a b) where
   top = Right top
   bottom = Left bottom
 
-instance foldableEither :: Foldable (Either a) where
-  foldr _ z (Left _)  = z
-  foldr f z (Right x) = f x z
-  foldl _ z (Left _)  = z
-  foldl f z (Right x) = f z x
-  foldMap f (Left _)  = mempty
-  foldMap f (Right x) = f x
-
-instance foldableWithIndexEither :: FoldableWithIndex Unit (Either a) where
-  foldrWithIndex _ z (Left _)  = z
-  foldrWithIndex f z (Right x) = f unit x z
-  foldlWithIndex _ z (Left _)  = z
-  foldlWithIndex f z (Right x) = f unit z x
-  foldMapWithIndex f (Left _)  = mempty
-  foldMapWithIndex f (Right x) = f unit x
-
-instance bifoldableEither :: Bifoldable Either where
-  bifoldr f _ z (Left a) = f a z
-  bifoldr _ g z (Right b) = g b z
-  bifoldl f _ z (Left a) = f z a
-  bifoldl _ g z (Right b) = g z b
-  bifoldMap f _ (Left a) = f a
-  bifoldMap _ g (Right b) = g b
-
-instance traversableEither :: Traversable (Either a) where
-  traverse _ (Left x)  = pure (Left x)
-  traverse f (Right x) = Right <$> f x
-  sequence (Left x) = pure (Left x)
-  sequence (Right x)  = Right <$> x
-
-instance traversableWithIndexEither :: TraversableWithIndex Unit (Either a) where
-  traverseWithIndex _ (Left x)  = pure (Left x)
-  traverseWithIndex f (Right x) = Right <$> f unit x
-
-instance bitraversableEither :: Bitraversable Either where
-  bitraverse f _ (Left a) = Left <$> f a
-  bitraverse _ g (Right b) = Right <$> g b
-  bisequence (Left a) = Left <$> a
-  bisequence (Right b) = Right <$> b
-
 instance semigroupEither :: (Semigroup b) => Semigroup (Either a b) where
   append x y = append <$> x <*> y