Make sure strict folds force all the spine.

Not only the next few links, but any number of links. Even if an
undefined link is very far, make sure it is still forced.

Author: kindaro

tests/Properties.hs

@@ -249,9 +249,9 @@ explosiveTail :: B -> B
 explosiveTail = (<> error "Tail of this byte string is undefined!")
 
 prop_Lfoldr_lazy = \ xs -> genericTake (L.length xs) (L.foldr (:) [ ] (explosiveTail xs)) == L.unpack xs
-prop_Lfoldr'_strict = expectFailure $ \ xs -> genericTake (L.length xs) (L.foldr' (:) [ ] (explosiveTail xs)) == L.unpack xs
+prop_Lfoldr'_strict = expectFailure $ \ xs ys -> genericTake (L.length xs) (L.foldr' (:) [ ] (explosiveTail (xs <> ys))) == L.unpack xs
 prop_Lfoldr1_lazy = \ xs -> L.length xs > 0 ==> L.foldr1 const (explosiveTail (xs <> L.singleton 1)) == L.head xs
-prop_Lfoldr1'_strict = expectFailure $ \ xs -> L.length xs > 0 ==> L.foldr1' const (explosiveTail xs) == L.head xs
+prop_Lfoldr1'_strict = expectFailure $ \ xs ys -> L.length xs > 0 ==> L.foldr1' const (explosiveTail (xs <> ys)) == L.head xs
 
 prop_unfoldrBP   =
   forAll arbitrarySizedIntegral $