#3631: Overload the Prelude iterate to support list input
---------------------------------+------------------------------------------
Reporter: shelbymoore3 | Owner:
Type: feature request | Status: closed
Priority: normal | Milestone:
Component: Prelude | Version: 6.10.4
Severity: normal | Resolution: wontfix
Keywords: | Difficulty: Unknown
Testcase: | Os: Unknown/Multiple
Architecture: Unknown/Multiple |
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Comment (by shelbymoore3):
Actually none of that above works, we need instead an accumulator argument
for the list, which solves the collision problem with standard Prelude
`iterate` also:
{{{
iterate :: ([a] -> [a]) -> [a] -> [a] -> [a]
iterate f x y = y ++ iterate f (x ++ (f (x ++ y))) (f (x ++ y))
}}}
{{{
fibs = 0 : 1 : iterate (\x -> [last x + last init x]) [ 0 : 1 ] [] where
}}}
IMHO, it is not most productive to mark useful input as "Won't fix", and
have it disappear into a black-hole. It is more productive to mark as
"Incomplete" and let people apply their effort later to make it complete,
as has now been done. "Won't fix" should apply to something that should
not be fixed (an entirely erroneous report with no chance of being ever
fixed), not to something that is in a useful direction, but incomplete.
"Won't fix" is effectually little different than a moral judgment, because
it is a black hole. It is analogous to telling someone sorry you were
misclassified on the "do not fly list" and are spending the rest of your
vacation in a DHS holding area, but be comforted that it was not a moral
mis-classification. Who cares. Give me back my vacation and my wasted
time.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3631#comment:14>
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