Fwd: Is anything being done to remedy the soul crushing compile times of GHC?

Herbert Valerio Riedel hvriedel at gmail.com
Thu Feb 18 12:43:00 UTC 2016

On 2016-02-18 at 13:32:59 +0100, Andrey Mokhov wrote:


> Interesting! In the new Shake-based build system we also need to
> automagically generate .hs files using Alex et al. My first
> implementation was slow but then I realised that it is possible to
> scan the source tree only once and remember where all .hs/.x/etc files
> are. This brought down the complexity from quadratic to linear in my
> case -- maybe this could be reused in cabal too?

This sounds very risky; are you suggesting to blindly traverse the
hs-src-dirs *before* you even know what is searched for?

If so, this will cause problems; we're already seeing problems with this
in the cabal nix-local-branch, which currently (it's a bug) recursively
traverses the project folder for computing a source-hash over content
that would not even make it into the source-dist...

There must be a better way to solve this...

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