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import Control.Exception (evaluate)
import qualified Data.List as L
-- The following will fuse with minimal heap usage provided
-- `findIndices` is marked `INLINABLE` instead of `INLINE`.
unsafeFindIndex p = head . L.findIndices p
main = do evaluate $ L.elemIndex 999999 [(1::Int)..1000000]
evaluate $ L.elemIndices 999999 [(1::Int)..1000000]
evaluate $ L.findIndex (>=999999) [(1::Int)..1000000]
evaluate $ L.findIndices (>=999999) [(1::Int)..1000000]
evaluate $ unsafeFindIndex (>=999999) [(1::Int)..1000000]
{- Note; see !7997.
You would think those [1..100000] sub-expressions would float to the
top level, be CSE'd, and shared.
But no: until May 22-ish, they are the argument of a strict function
findIndices; and in HEAD SetLevels goes to some trouble not to float
strict arguments. So in HEAD, no sharing happens.
I think the reasoning is bogus, so I changed in; see
"Arguments" in Note [Floating to the top] in SetLevels.
As a result these lists are now floated out and shared.
Just leaving breadcrumbs, in case we later see big perf changes on
this (slightly fragile) benchmark.
-}
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