I've recently been wondering (in a more general context than just haskell)
about optimisations along the lines of
foo x y z = if complicated thing then Cons1 a b c
else if other complicated thing then Cons2 d e
else Cons3 f
bar some args = case foo perhaps different args of
Cons1 a b c -> code for case one
Cons2 a b -> code for case two
Cons3 a -> code for case three
into
foo x y z k1 k2 k3 =
if complicated thing then k1 a b c
else if other complicated thing then k2 d e
else k3 f
bar some args = foo perhaps different args
(\ a b c -> code for case one)
(\ a b -> code for case two)
(\ a -> code for case three)
Such that you save a cons (unless the compiler can return the value in
registers or on the stack) and a case analysis branch, but a normal
function return (predictable by the CPU) is replaced by a less-predictable
indirect jump. Does anyone have references to a paper that discusses an
optimisation like this for any language, not just Haskell?
Tony.
--
f.a.n.finch <[EMAIL PROTECTED]> http://dotat.at/
SHANNON ROCKALL: VARIABLE 3, BECOMING SOUTH OR SOUTHEAST 4 OR 5, OCCASIONALLY
6, VEERING WEST LATER. MODERATE OR ROUGH. RAIN WITH FOG PATCHES, SHOWERS
LATER. MODERATE OR GOOD, OCCASIONALLY VERY POOR.
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