newly defined subtype doesn't play well as part of union
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Nobody has claimed this yet.
- Dominant language
- Racket
- Stars
- 575
- Forks
- 106
- Avg merge
- 2h 1m
- Merged PRs (30d)
- 2
Description
What version of Racket are you using?
v6.6.0.2
What program did you run?
#lang typed/racket/base
(define-new-subtype New-Int (integer->new-int Integer))
(define-type T (U String New-Int))
(ann (integer->new-int 42) T)
What should have happened?
The above program's last line does not type check.
If you got an error message, please include it here.
; Type Checker: type mismatch
; expected: T
; given: New-Int
; in: (integer->new-int 42)
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
Start by running the provided Typed Racket program and inspecting how define-new-subtype interacts with union type checking. Done means the final ann expression type checks with T defined as (U String New-Int), without changing the demonstrated program's intended types.
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
- Clearly specified
- Newbie friendliness
- 35/100