Unification not working on simple expected case.
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Description
Prerequisites
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Description
example (a b c : Nat) : a = b → a * c = b * c := congrArg _ --fails, works with (· * c) requires you to explicitly spell out the function. In lean3, this is not required, and often used in mathlib.
Expected behavior: Success.
Actual behavior:
type mismatch
congrArg ?m.56535
has type
?m.56533 = ?m.56534 → ?m.56535 ?m.56533 = ?m.56535 ?m.56534 : Prop
but is expected to have type
a = b → a * c = b * c : Prop
Reproduces how often: 100%
Versions
Lean (version 4.0.0-nightly-2023-01-16, commit 5349a089e5bb, Release)
OSX Ventura 13.1, M1 Mac
Contributor guide
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 reproducing the supplied Lean 4 example using the reported nightly version and compare congrArg _ with (· * c). The issue names no source file or test entry point; done means the expected example succeeds without explicitly spelling out the function.
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