Internal Typechecker Error: Base type L+ not in predefined-type-table
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- Dominant language
- Racket
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- 575
- Forks
- 106
- Avg merge
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- Merged PRs (30d)
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Description
What version of Racket are you using?
6.6.0.4
What program did you run?
#lang typed/racket
(define-type (L+ T REST) (Pairof T (∩ (L+ T Any) REST)))
What should have happened?
A better error message. I was fiddling around with types, trying to see if I could describe the type for a pair of same-length lists (I don't think it's possible), so the code above isn't supposed to work anyway.
If you got an error message, please include it here.
.../share/racket/pkgs/typed-racket-lib/typed-racket/utils/tc-utils.rkt:270:0: Internal Typechecker Error: Base type L+ not in predefined-type-table
while typechecking:
here
originally:
here
The problematic definition is not highlighted in red (so in a larger file, it would be harder to find), and the "while typechecking: here originally: here" is not particularly helpful :) .
Contributor guide
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First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Reproduce the issue with the provided typed/racket definition, then inspect typed-racket/utils/tc-utils.rkt around line 270 and the surrounding typechecker diagnostics. Done should replace the internal typechecker error with a useful message that identifies the problematic definition and improves its source highlighting.
Written by the indexing model from the issue text.
Assessment
- Domain
- compilers
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 42/100