Lifted error when using opaque type that is declared later
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- Dominant language
- Racket
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- 575
- Forks
- 106
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Description
What version of Racket are you using?
6.6.0.4
What program did you run?
#lang typed/racket/base
(require/typed racket [identity (→ MyList MyList)])
(require/typed racket [#:opaque MyList list?])
If you got an error message, please include it here.
The program compiles fine with raco make, but fails at run-time with:
list?2.0: undefined;
cannot reference an identifier before its definition
What should have happened?
The program should either fail to compile, or succeed at run-time.
The following program (where the two lines have been swapped) compiles and runs fine:
#lang typed/racket/base
(require/typed racket [#:opaque MyList list?])
(require/typed racket [identity (→ MyList MyList)])
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 two typed/racket/base examples from the issue with raco make and at runtime, comparing the original and swapped require/typed order. Investigate how the opaque MyList declaration and the identity type reference are processed, then ensure the program either reports the ordering problem at compile time or runs successfully without the undefined-identifier error.
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
- 35/100