[Haskell-beginners] coming to grips with hackage

[Heinrich Apfelmus]

Brandon Allbery wrote:
> I do find myself wondering if anyone has checked to see how important the
> inlining is these days; perhaps ghc's general performance (and a hat tip to
> Moore's law) has made it possible to consider compiling more stable
> libraries.

Lately, I have been looking at GHC Core output for unrelated reasons, 
and it appears to me that cross-module inlining is essential to GHC 
performance.

For instance, if you don't inline the monadic combinators (>>=) and 
`return` for the IO monad and perform even more inlining afterwards, 
performance can easily differ by an order of magnitude. The reason is 
that the second argument of (>>=) is a closure. Closure creation is very 
expensive compared to the sequence of primops you get after inlining.


Best regards,
Heinrich Apfelmus

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