ab606ba754
This PR provides an additional hint when the type of an autobound implicit is required to have function type or equality type — this fails, and the existing error message does not address the fact that the source of the error is an unknown identifier that was automatically bound. ## Example ``` import Lean example : MetaM String := pure "" ``` Current error message: ``` Function expected at MetaM but this term has type ?m Note: Expected a function because this term is being applied to the argument String ``` Additional error message provided by this PR: ``` Hint: The identifier `MetaM` is unknown, and Lean's `autoImplicit` option causes an unknown identifier to be treated as an implicitly bound variable with an unknown type. However, the unknown type cannot be a function, and a function is what Lean expects here. This is often the result of a typo or a missing `import` or `open` statement. ```
11 lines
610 B
Text
11 lines
610 B
Text
3989_2.lean:6:0: error: expected else-alternative for `match_expr`, i.e., `| _ => ...`
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3989_2.lean:1:22-1:32: error: Function expected at
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MetaM
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but this term has type
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?m
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Note: Expected a function because this term is being applied to the argument
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Expr
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Hint: The identifier `MetaM` is unknown, and Lean's `autoImplicit` option causes an unknown identifier to be treated as an implicitly bound variable with an unknown type. However, the unknown type cannot be a function, and a function is what Lean expects here. This is often the result of a typo or a missing `import` or `open` statement.
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Nat : Type
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