dhall-to-cabal performance has regressed

[ocharles]

For 1.0.0.1

$ time ./dist/build/dhall-to-cabal/dhall-to-cabal dhall-to-cabal.dhall

real	0m6.735s
user	0m6.628s
sys	0m0.106s

For 1.1.0.0

$ time ./dist/build/dhall-to-cabal/dhall-to-cabal dhall-to-cabal.dhall

real	0m53.553s
user	0m52.914s
sys	0m0.562s

Ouch! Hopefully @quasicomputational's work on Dhall itself will help fix this.

[ocharles]

Looking much better in 1.2.0.0

$ time time ./dist-newstyle/build/x86_64-linux/ghc-8.2.2/dhall-to-cabal-1.2.0.0/x/dhall-to-cabal/build/dhall-to-cabal/dhall-to-cabal dhall-to-cabal.dhall

real	0m9.900s
user	0m9.815s
sys	0m0.084s

[ocharles]

Unfortunately a little slower in 1.3.0.0 (though this might be due to a different machine, can't remember where I last ran this test).

real    0m13.515s
user    0m13.378s
sys     0m0.136s

[ocharles]

Slower again with dhall-1.18.0:

[nix-shell:~/work/dhall-to-cabal]$ time /home/ollie/work/dhall-to-cabal/dist-newstyle/build/x86_64-linux/ghc-8.2.2/dhall-to-cabal-1.4.0.0/x/dhall-to-cabal/build/dhall-to-cabal/dhall-to-cabal dhall-to-cabal.dhall > /dev/null

real    0m14.675s
user    0m14.555s
sys     0m0.116s

[jneira]

Ugh, it should be faster this time 😞
I did a pair of profiles of dhall < dhall-to-cabal.dhall after the new impl map changes: dhall-lang/dhall-haskell#612 (comment), dhall-lang/dhall-haskell#612 (comment)

[ocharles]

Yep, I was hoping for a change (for the better!) but unfortunately it hasn't come out that way 😢

[jneira]

I've updated the related dhall-haskell issue with the new resultas using the new union direct access: dhall-lang/dhall-haskell#412 (comment)

dhall-to.cabal has improved a 200%:

• before direct access:

dhall-to-cabal:           OK (16.17s) 

• after:

dhall-to-cabal:           OK (5.35s)

[ocharles]

For dhall-to-cabal-1.3.2.0 (Dhall 1.20.1):

[nix-shell:~/work/dhall-to-cabal]$ time ./dist-newstyle/build/x86_64-linux/ghc-8.2.2/dhall-to-cabal-1.3.2.0/x/dhall-to-cabal/build/dhall-to-cabal/dhall-to-cabal dhall-to-cabal.dhall
Writing to dhall-to-cabal.cabal.

real    0m2.886s
user    0m2.838s
sys     0m0.048s

Very nice improvement! CC @Gabriel439

[ocharles]

More progress in dhall-to-cabal-1.3.3.0 using dhall-1.23.0:

[nix-shell:~/work/dhall-to-cabal]$ time /home/ollie/work/dhall-to-cabal/dist-newstyle/build/x86_64-linux/ghc-8.2.2/dhall-to-cabal-1.3.3.0/x/dhall-to-cabal/build/dhall-to-cabal/dhall-to-cabal dhall-to-cabal.dhall 
Writing to dhall-to-cabal.cabal.

real    0m1.927s
user    0m1.874s
sys     0m0.034s