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{-# OPTIONS_GHC -fglasgow-exts -O -ddump-prep #-}
module Max(result) where
foo ys = foldr (\x xs -> x : reverse xs) [] ys
result xs =
let stuff = [1, 1, 1, 1, 1, 1]
in foo (reverse stuff)
-- What used to happen is that foldr got expanded by main simplification
-- and the resulting "go" function got floated out but because we manufactured
-- a new binder for it in newPolyBndrs we would lose its demand signature!
-- This means that the later application of it in result did not use call by value :-(
-- Eyeball test:
-- Ensure that Max.poly_go has a demand signature
-- Ensure that we use call by value to call Max.poly_go in result
-- i.e. the call to Max.poly_go inside Max.result looks like this:
--
-- case GHC.List.poly_rev @ t1_a6x sat_seb (GHC.Base.[] @ t1_a6x)
-- of sat_sed { __DEFAULT ->
-- Max.poly_go @ t1_a6x sat_sed
-- } } in
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