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

Ben Gamari ben at smart-cactus.org
Wed Feb 17 20:00:38 UTC 2016

Tuncer Ayaz <tuncer.ayaz at gmail.com> writes:

> On 17 February 2016 at 07:40, Evan Laforge <qdunkan at gmail.com> wrote:
>> My impression from the reddit thread is that three things are going
>> on:
>> 1 - cabal has quite a bit of startup overhead
>> 2 - ghc takes a long time on certain inputs, e.g. long list literals.
>> There are probably already tickets for these.
> In my experience GHC startup overhead (time) has increased quite a lot
> somewhere in 7.x. I don't know if it's the cause, but perhaps dyn libs
> may be part of the reason. I'm not sure because I once (7.8 I believe)
> tried to build without dynlink support and couldn't measure a
> substantial improvement.
I'm not sure this is going to be a significant effect, but last night
thomie, rwbarton, and I discovered that the way we structure the Haskell
library directory makes the dynamic linker do significantly more work than
necessary. Merely compiling "Hello world" requires 800 `open` system
calls with a dynamically linked compiler. Seems like we should really
try to fix this. See #11587.


- Ben
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