e804829101
This PR modifies `#eval e` to elaborate `e` with section variables in scope. While evaluating expressions with free variables is not possible, this lets `#eval` give a better error message than "unknown identifier." Example: ```lean section variable (n : Nat) /-- error: Cannot evaluate, contains free variable `n` -/ #guard_msgs in #eval n end ``` The error is localized to `#eval`. It would be more friendly if the error were to be placed on uses of free variables. [Zulip discussion](https://leanprover.zulipchat.com/#narrow/channel/270676-lean4/topic/Unknown.20identifier.20error.20messages.20for.20.60.23eval.60/near/560864544)
43 lines
885 B
Text
43 lines
885 B
Text
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/--
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error: Tactic `decide` proved that the proposition
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False
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is false
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-/
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#guard_msgs in
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#eval show Nat from False.elim (by decide)
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/--
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error: Aborting evaluation since the expression depends on the 'sorry' axiom, which can lead to runtime instability and crashes.
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To attempt to evaluate anyway despite the risks, use the '#eval!' command.
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---
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warning: declaration uses `sorry`
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-/
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#guard_msgs in
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#eval #[1,2,3][2]'sorry
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/--
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info: 3
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---
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warning: declaration uses `sorry`
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-/
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#guard_msgs in
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#eval! #[1,2,3][2]'sorry
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/-
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With this test I wanted to show that `#eval!` can be used to do unsafe operations. Under
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normal circumstances this actually works with the output below, but the `Linux Debug` CI build
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catches it and complains. Maybe too bold to have this in the test suite.
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/--
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warning: declaration uses `sorry`
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---
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info: 3
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-/
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#guard_msgs in
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#eval! (#[1,2,3].pop)[2]'sorry
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-/
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