How to turn LHExpr GhcPs into CoreExpr

Richard Eisenberg rae at
Thu Jan 23 09:04:03 UTC 2020

I don't know the exact semantics of the interactive context, etc., but that looks plausible. It won't give the *wrong* answer. :)

Thanks for sharing!

> On Jan 23, 2020, at 4:52 AM, Yiyun Liu <liuyiyun at> wrote:
> Thank you all for your help! It turns out that I was missing the constraint solving and zonking step by desugaring the result of tcInferSigma directly.
> I have the implementation of the function here <>. Not sure if it's 100% correct but at least it works for all the examples I can come up with so far.
> - Yiyun
> On 1/22/20 7:09 AM, Andreas Klebinger wrote:
>> I tried this for fun a while ago and ran into the issue of needing to provide a type environment containing Prelude and so on.
>> I gave up on that when some of the calls failed because I must have missed to set up some implicit state properly.
>> I didn't have an actual use case (only curiosity) so I didn't look further into it. If you do find a way please let me know.
>> I would also support adding any missing functions to GHC-the-library to make this possible if any turn out to be required.
>> As an alternative you could also use the GHCi approach of using a fake Module. This would allow you to copy whatever GHCi is doing.
>> But I expect that to be slower if you expect to process many such strings, 
>> Richard Eisenberg schrieb am 22.01.2020 um 10:36:
>>> You'll need to run the expression through the whole pipeline.
>>> 1. Parsing
>>> 2. Renaming
>>> 3. Type-checking
>>>   3a. Constraint generation
>>>   3b. Constraint solving
>>>   3c. Zonking
>>> 4. Desugaring

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