[Haskell-cafe] Re: Experiments with defunctionalization,
church-encoding and CPS
apfelmus at quantentunnel.de
Sun Nov 1 12:31:43 EST 2009
David Menendez wrote:
> On Sun, Nov 1, 2009 at 7:12 AM, Heinrich Apfelmus
> <apfelmus at quantentunnel.de> wrote:
>> Even then, the results are mixed. The Church-encoding shines in GHCi as
>> it should, but loses its advantage when the code is being compiled. I
>> guess we have to look at the core if we want to know what exactly is
>> going on.
> What optimization level did you compile with?
No optimization. From the bottom of the paste
In ghci, the church encodings clearly win.
*Main> force testTree
(1.63 secs, 13948748 bytes)
*Main> test findMaybe 0
(1.70 secs, 15026356 bytes)
*Main> test findChurch 0
(0.72 secs, 15553668 bytes)
*Main> test findChurch' 0
(0.71 secs, 13456600 bytes)
But when compiling, the algebraic data types wins.
ghc --make Test.hs
mean: 90.08407 ms, lb 86.36974 ms, ub 94.13646 ms
mean: 152.0198 ms, lb 144.0916 ms, ub 161.0063 ms
Church encoding optimised
mean: 114.0715 ms, lb 107.3498 ms, ub 122.6881 ms
I am a bit surprised. Then again, I probably shouldn't be surprised that
the cost model is not like I imagine it to be.
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