Lean 4 fork for HoTT-compatible kernel extensions (Path types, transport, HITs). Maintained against upstream leanprover/lean4.
9b74c07767
This PR ensures that the branches of an `if-then-else` term are internalized only after establishing the truth value of the condition. This change makes its behavior consistent with the `match`-expression and dependent `if-then-else` behavior in `grind`. This feature is particularly important for recursive functions defined by well-founded recursion and `if-then-else`. Without lazy `if-then-else` branch internalization, the equation theorem for the recursive function would unfold until reaching the generation depth threshold, and before performing any case analysis. See new tests for an example. |
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