Add support for record puns

[Gabriella439]

... as standardized in dhall-lang/dhall-lang#938

[sjakobi]

I've pushed a patch that should fix nix-build.

[sjakobi]

I think these glob entries wouldn't include test files like tests/import/success/unit/AlternativeChain1A.dhall. We might be missing a bunch of test cases then, at least when running them with nix.

[Gabriella439]

@sjakobi: Yeah, we are likely missing a bunch of test cases, especially after the refactor. I believe newer versions of Cabal support ** syntax for globbing through nested directories, so then we would be able to write: dhall-lang/tests/**.dhall

[sjakobi]

Yeah, the syntax is a bit more complicated and inconvient though: https://cabal.readthedocs.io/en/latest/file-format-changelog.html#cabal-version-2-4

I hope requiring Cabal-2.4 is ok. I think it would make building with Nix and GHC < 8.6 more tricky though.

In any case, I think we should address this issue separately.

[sjakobi]

Hydra reports two test failures in https://hydra.dhall-lang.org/build/54229/nixlog/5:

./dhall-lang/tests/type-inference/success/CacheImportsCanonicalize:
Testing without real HTTP support -- using mock HTTP client to resolve remote import.
FAIL
        tests/Dhall/Test/TypeInference.hs:64:
        user error ((mock http) Url does not match any of the hard-coded rules: https://csrng.net/csrng/csrng.php?min=0&max=1000)

./dhall-lang/tests/type-inference/success/CacheImports:
Testing without real HTTP support -- using mock HTTP client to resolve remote import.
FAIL
        tests/Dhall/Test/TypeInference.hs:64:
        user error ((mock http) Url does not match any of the hard-coded rules: https://csrng.net/csrng/csrng.php?min=0&max=1000)

[sjakobi]

I'm confused why such tests would live in the type-inference directory…

[sjakobi]

My last commit should handle the two CacheImports test failures. When running the tests locally I'm seeing a different issue though:

$ cabal test dhall:tasty -w ghc-8.6.5 --test-show-details=streaming --test-options "--hide-successes"
...
Test suite tasty: RUNNING...
Dhall Tests
  import tests
    discover
      ./dhall-lang/tests/import/success/unit/asLocation/HashA.dhall:                                                           PASS (unexpected)
        (unexpected success)

1 out of 1560 tests failed (10.75s)
...

[sjakobi]

I think I might have had some old state in my dhall/.cache affecting the results. After cleaning it, all tests behave as expected, both with cabal and stack.

[sjakobi]

I think the Travis failure with

An error occurred while generating the build script.

…is probably safe to ignore.

[Gabriella439]

@sjakobi: Yeah, I think it was a temporary Travis outage. I'll rerun it