Hello Simon,

I was about to send an improved version of D1801, I will do that once I rebase past your patch (there's a small overlap with what I've done). D1820 is ready for review.

I have a patch coming for piResultTys [1] where the FVs of ty are not in the in_scope set. I've also looked at a similar problem in lint_app [2], but the fix I have is a bit awkward, so I will probably need some input from you. Both of them are blocking #11360 and I want to get it unblocked as soon as possible to continue determinism work.

I'm aware of substTys being currently unchecked, I didn't want to introduce substTysUnchecked just yet, as there already are more than 30 occurrences of substTyUnchecked. But maybe I should push uncheckedness as far up as possible, do you think it's worth to do it now?

Do you want me to do the renaming?

Cheers,

Bartosz

[1] https://phabricator.haskell.org/diffusion/GHC/browse/master/compiler/types/Type.hs;016a0bd1ba129134dfa612db0d96e01644fa7b9f$803-804

[2] https://phabricator.haskell.org/diffusion/GHC/browse/master/compiler/coreSyn/CoreLint.hs;016a0bd1ba129134dfa612db0d96e01644fa7b9f$1134

2016-01-26 10:55 GMT+00:00 Simon Peyton Jones <simonpj@microsoft.com>:

Bartosz

How are you getting on with tidying up substitutions.

I’ve done a bit in that direction myself:

commit 1c6d70c2121fd1126fcc2458bdbcc856e19598c2

Author: Simon Peyton Jones <simonpj@microsoft.com>

Date:   Tue Jan 26 09:37:06 2016 +0000

    Kill off zipTopTCvSubst in favour of zipOpenTCvSubst

But there is more to do.

In particular, I note that substTys is not checked – but neither is it called substTysUnchecked. It should be! That will show up a bunch more cases, I think.

Another particular thing, arising from my patch, is that we can now do some renaming

·         zipOpenTCvSubst -> zipTvSubst   (It only deals with tyvars)

·         zipOpenTCvSubstCoVars -> zipCvSubst   (it only deals with covars)

·         zipOpenTCvSubstBinders -> zipTyBinderSubst (it only deals with TyBinders, not covars)

I guess you’ll want to do similar things for the “mk” variants.

Anyway: good for you! Let me know if you need help.

Simon