7d60d8b563
previously, `#eval` would happily evaluate expressions that contain `sorry`, either explicitly or because of failing tactics. In conjunction with operations like array access this can lead to the lean process crashing, which isn't particularly great. So how `#eval` will refuse to run code that (transitively) depends on the `sorry` axiom (using the same code as `#print axioms`). If the user really wants to run it, they can use `#eval!`. Closes #1697
37 lines
894 B
Text
37 lines
894 B
Text
import Lean
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open Lean Elab Meta
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def somethingBad : MetaM Nat := do
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IO.println "oh no"
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return 1
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/--
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error: invalid use of `(<- ...)`, must be nested inside a 'do' expression
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---
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error: cannot evaluate expression that depends on the `sorry` axiom.
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Use `#eval!` to evaluate nevertheless (which may cause lean to crash).
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-/
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#guard_msgs in
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#eval show MetaM Unit from do
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let t := if false then ← somethingBad else 9
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def foo : MetaM Bool :=
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return false
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/--
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error: invalid use of `(<- ...)`, must be nested inside a 'do' expression
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---
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error: cannot evaluate expression that depends on the `sorry` axiom.
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Use `#eval!` to evaluate nevertheless (which may cause lean to crash).
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-/
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#guard_msgs in
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#eval show MetaM Unit from do
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let t := if (← foo) then ← somethingBad else 9
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/--
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info: 1
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-/
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#guard_msgs in
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#eval show MetaM Nat from do
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let t := if (← foo) then 0 else 1
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return t
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