Newtype-derive Unfoldable1 instance for NonEmptyArray

Author: garyb

src/Data/Array/NonEmpty/Internal.js

@@ -11,27 +11,6 @@ exports.fold1Impl = function (f) {
   };
 };
 
-exports.unfoldr1Impl = function (isNothing) {
-  return function (fromJust) {
-    return function (fst) {
-      return function (snd) {
-        return function (f) {
-          return function (value) {
-            var result = [];
-            while (true) { // eslint-disable-line no-constant-condition
-              var tuple = f(value);
-              result.push(fst(tuple));
-              var maybe = snd(tuple);
-              if (isNothing(maybe)) return result;
-              value = fromJust(maybe); // eslint-disable-line no-param-reassign
-            }
-          };
-        };
-      };
-    };
-  };
-};
-
 exports.traverse1Impl = function () {
   function Cont(fn) {
     this.fn = fn;

src/Data/Array/NonEmpty/Internal.purs

@@ -7,15 +7,12 @@ import Data.Eq (class Eq1)
 import Data.Foldable (class Foldable)
 import Data.FoldableWithIndex (class FoldableWithIndex)
 import Data.FunctorWithIndex (class FunctorWithIndex)
-import Data.Maybe (Maybe, fromJust, isNothing)
 import Data.Ord (class Ord1)
 import Data.Semigroup.Foldable (class Foldable1, foldMap1Default)
 import Data.Semigroup.Traversable (class Traversable1, sequence1Default)
 import Data.Traversable (class Traversable)
 import Data.TraversableWithIndex (class TraversableWithIndex)
-import Data.Tuple (Tuple, fst, snd)
 import Data.Unfoldable1 (class Unfoldable1)
-import Partial.Unsafe (unsafePartial)
 
 newtype NonEmptyArray a = NonEmptyArray (Array a)
 
@@ -40,9 +37,7 @@ instance foldable1NonEmptyArray :: Foldable1 NonEmptyArray where
   foldMap1 = foldMap1Default
   fold1 = fold1Impl (<>)
 
-instance unfoldable1NonEmptyArray :: Unfoldable1 NonEmptyArray where
-  unfoldr1 = unfoldr1Impl isNothing (unsafePartial fromJust) fst snd
-
+derive newtype instance unfoldable1NonEmptyArray :: Unfoldable1 NonEmptyArray
 derive newtype instance traversableNonEmptyArray :: Traversable NonEmptyArray
 derive newtype instance traversableWithIndexNonEmptyArray :: TraversableWithIndex Int NonEmptyArray
 
@@ -63,16 +58,6 @@ derive newtype instance altNonEmptyArray :: Alt NonEmptyArray
 -- we use FFI here to avoid the unncessary copy created by `tail`
 foreign import fold1Impl :: forall a. (a -> a -> a) -> NonEmptyArray a -> a
 
-foreign import unfoldr1Impl
-  :: forall a b
-   . (forall x. Maybe x -> Boolean)
-  -> (forall x. Maybe x -> x)
-  -> (forall x y. Tuple x y -> x)
-  -> (forall x y. Tuple x y -> y)
-  -> (b -> Tuple a (Maybe b))
-  -> b
-  -> NonEmptyArray a
-
 foreign import traverse1Impl
   :: forall m a b
    . (forall a' b'. (m (a' -> b') -> m a' -> m b'))