On Tuesday 10 July 2007, Tony Morris wrote:
> Thanks Don,
> Is your explanation specific to maybe? Or does that apply to all functions?
>
> Suppose the following function for lists:
>
> f :: [a] -> b -> (a -> [a] -> b) -> b
>
> ...instead of pattern matching [] and (x:xs)
Of course. GHC doesn't know anything about maybe; all it sees is:
1. One-liner:
maybe f x mb = case mb of { Just x' -> f x'; Nothing -> x }
2. Non-recursive
And it inlines like crazy. If you had quite a large data type, the number of
case alternatives /might/ put you over GHC's inlining threshold, but that
(ridiculous) scenario is the only thing that'll keep the argument from
generalizing to your use case.
<snip>
Jonathan Cast
http://sourceforge.net/projects/fid-core
http://sourceforge.net/projects/fid-emacs
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