[plt-scheme] Check for function equality?

From: Prabhakar Ragde (plragde at uwaterloo.ca)
Date: Thu Feb 19 19:15:07 EST 2009

Matthew Flatt wrote:

>> > Is there a Scheme function similar to "check-expect" that tests for
>> > equality between functions?
> No.
> Apologies if you already know this and I misunderstand the question,
> but: That's not the sort of thing that can be detected or proved in
> general. Look for information on the "halting problem" for details.

I'm surprised that you didn't mention that the very first problem to be 
proved uncomputable, before the halting problem, was the problem of 
equivalence of two expressions in the lambda calculus [Church 1936]. Of 
course, understanding this via the halting problem is much simpler, and 
that's the way we teach it nowadays. --PR

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