[Haskell-cafe] ghc -O2 out of memory

Bardur Arantsson spam at scientician.net
Sat Mar 7 18:26:19 UTC 2015

On 07-03-2015 16:56, Kees Bleijenberg wrote:
> I've written a program that reads a Excel file, parses the contents and
> generates a haskell module. Every cell in the xls has it's own function in
> the module. This worked fine. 
> Now I have a bigger xls. The resulting module Xls.hs contains 30000 lines
> haskell code (without comment). I created a testprogram test.hs that
> calculates and prints one cell.
> I did ghc --make test.hs and everything works fine.  The generated
> execuatable is very slow.
> I did ghc --make -O2 test.hs. The compilations takes 15 minutes and aborts
> with   'ghc: out of memory'. I'am working on Win 7 64 bits , ghc version =
> 7.8.3.
> What can I do to fix this? I do need -O2. I found with smaller xls's that
> optimization speeds up the executable dramatically.
> Before I start experimenting, does it help to split up the xls .hs in
> seperate  files? I.e. the cells that refer to other cells and cells that
> don't refer to other cells. Or will I still get 'out of memory' because the
> optimization is global?

Just out of curiousity, are you adding explicit type annotations? I
imagine that type inference (rather than just checking) would add
considerable overhead in pathological cases, especially if GHC is using
a SAT-solver based approach (which I believe it is, these days).


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