[Haskell-cafe] ANN: HLint 1.2

[Max Bolingbroke]

2009/1/12 Jan-Willem Maessen <jmaessen at alum.mit.edu>:
> On Jan 12, 2009, at 9:01 AM, Duncan Coutts wrote:
>
>> No because the current definition are recursive and ghc cannot inline
>> recursive functions.
>>
>> ....
>>
>> Then the map can be inlined at the call site and the 'f' inlined into
>> the body of 'go'.
>
> This seems like exactly the sort of mechanical transformation that computers
> do quickly and accurately, and humans get wrong.  Surely it wouldn't be that
> hard for GHC to transform self recursion in this way (possibly subject to
> the condition that the result be worth inlining)?

GHC should indeed be doing so. I'm working (on and off) to work out
some suitable heuristics and put the transformation into ghc -O2.
There are a few wrinkles that still need sorting out, but preliminary
indications are that it decreases the runtime of our standard
benchmark suite, nofib, by 12% or so.

Cheers,
Max