lean4-htt/tests/lean/run/postponeBinRelIssue.lean
Leonardo de Moura d3b0b49c43 feat: improve elabBinRelCore
See new test and comments at `elaBinRelCore`
2022-09-15 15:17:57 -07:00

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def as := [-1, 2, 0, -3, 4]
#eval as.map fun a => ite (GE.ge a 0) [a] [] -- Works
#eval as.map fun a => ite (a ≥ 0) [a] [] -- Fails if we use `withSynthesize` instead of `withSynthesizeLight` at `elabBinRel`
example : True :=
/-
Requires type annotation at the numeral, otherwise we get a type error at `rfl`
because `(0 == 1)` does not reduce to `false` until the default instance is applied.
Possible improvement: before reporting a type mismatch, apply default instances, and try again.
-/
have : (0 == (1 : Nat)) = false := rfl
⟨⟩