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

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! Richard

On Jan 23, 2020, at 4:52 AM, Yiyun Liu 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 https://github.com/yiyunliu/ghc-elaboration-test/blob/8f362ad92dc6601b4cb7e4.... 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

How about using `hscCompileCoreExprHook` to intercept the `CoreExpr` from the ghci pipeline? There exist GHC API to evaluate a String to a ForeignHValue iirc; we are not interested in the final ForeignHValue in this case, we just want the CoreExpr, and the logic of generating and linking BCO can be discarded. Cheers, Cheng On Thu, Jan 23, 2020 at 1:55 PM Ben Gamari wrote:

It is slightly disheartening that this relatively simple use-case requires reaching so deeply into the typechecker.

If there really exusts no easier interface then perhaps we should consider adopting your elaborateExpr as part of the GHC API.

Cheers,

- Ben

On January 23, 2020 4:04:03 AM EST, Richard Eisenberg wrote:

...

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! Richard

On Jan 23, 2020, at 4:52 AM, Yiyun Liu 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

-- Sent from my Android device with K-9 Mail. Please excuse my brevity. _______________________________________________ ghc-devs mailing list ghc-devs@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs