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joscoh
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aqjune-aws
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shigoel
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Issue #, if available:
Description of changes: Change semantics for equality to avoid returning
falsewhen two lambda or quantifier bodies are syntactically different, because this says nothing about whether or not they are semantically distinct. For example,\x.if true then 0 else 1and\x.0are syntactically different but semantically equal. This PR changes the semantics so that equalities of terms containing binders only reduce if they are syntactically equal; otherwise the semantics is stuck.Note that we will need to change the typing rules to prove progress, since evaluation can now get stuck on well-typed terms. But we will have to determine whether that involves a direct change to the typing rules, a change to canonical values, etc and it should be finalized once the type system is fully settled (it may change as a result of the future denotational semantics).
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