Aaron Denney <[EMAIL PROTECTED]> writes:
> With a recursive function of more than one argument, does it make sense
> to keep the arguments that tend to remain constant closer to the front?
>
> i.e.
>
> Will any implementations notice interp y x:xs calls interp y, and keep
> some sort of interp y partial application around?
Systems which perform lambda-lifting will usually be tuned this way,
as the same optimization also speeds up tail recursion. For example:
interp y xs = interpaux xs
where interpaux [] = ...
interpaux (x:xs) = ... interpaux xs ...
Will be lambda-lifted to the original interp definition, with an extra
call:
interp y xs = interpaux y xs
interpaux y [] = ...
interpaux y (x:xs) = ... interpaux y xs ...
This one of the reasons nhc does this optimization, I'm sure. I know
the Eager Haskell compiler avoids pushing and popping the invariant
arguments from the stack during a tail call; I recall that hbc does so
as well.
-Jan-Willem Maessen
Eager Haskell Project
[EMAIL PROTECTED]
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