Zulip Chat Archive

Stream: general

Topic: private and parameter

Andrew Yang (Sep 28 2021 at 04:07):

Consider this mwe

parameters (α : Type)
include α

private def foo : Type := α

#check foo /- foo : Type -/

example : Type := foo -- OK

example : Type := by exact foo
invalid type ascription, term has type
  Type → Type
but is expected to have type
α : Type
⊢ Type


Lean seems to revert the parameters when private defs or lemmas are used in a tactic block.
It successfully compiles if private is removed. Is it really the case or am I missing something?

Scott Morrison (Sep 28 2021 at 04:10):

Given that using either parameters or private is discouraged, I'm not too surprised if there are bad interactions that haven't been noticed. :-(

Mario Carneiro (Sep 28 2021 at 04:12):

This is a known issue with parameters even without the private: parameters don't work inside tactics (they act like variables instead)

Last updated: Dec 20 2023 at 11:08 UTC