GHC Core simplifier question: turn off all passes?

[Rahul Muttineni]

Hi Chris,

I think you're looking for -ddump-ds which outputs the Core just after the
desugarer is done. -ddump-simpl gives the Core after the simplifier is run.

Hope that helps,
Rahul

On Fri, Apr 7, 2017 at 6:25 PM, Christopher Done <chrisdone at gmail.com>
wrote:

> Hi all,
>
> Just checking, if I want to see the Haskell code desugared to core
> BEFORE any simplification passes, is this the way to do it?
>
> bash-3.2$ cat > X.hs
> module X where it = (\x -> x * 2) 123
> bash-3.2$ stack exec -- ghc -ddump-simpl X.hs -fforce-recomp
> -fmax-simplifier-iterations=0 -O0
> [1 of 1] Compiling X                ( X.hs, X.o )
>
> ==================== Tidy Core ====================
> Result size of Tidy Core = {terms: 11, types: 3, coercions: 0}
>
> -- RHS size: {terms: 4, types: 1, coercions: 0}
> it :: Integer
> [GblId, Str=DmdType]
> it = * @ Integer GHC.Num.$fNumInteger 123 2
>
> I was a bit surprised that the lambda is collapsed already with
> optimizations turned off and the simplifier iterations set to 0. I
> changed this to (\x -> x * x) and it produced a let instead. Is this
> just one of the things the HS->Core desugarer decides to do?
>
> Ciao!
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-- 
Rahul Muttineni
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