[plt-scheme] equal? and shared structure

From: Matthew Flatt (mflatt at cs.utah.edu)
Date: Wed Dec 19 07:49:51 EST 2007

At Tue, 18 Dec 2007 22:19:01 -0500, Prabhakar Ragde wrote:
> Under what circumstances will equal? terminate with the right answer 
> when given cons-structures with sharing (and possibly cycles)? The two I 
> concocted for homework seem not to break it, but others do.

`equal?' starts with an `eq?' test. If that happens to short-circuit a
cyclic comparison, then `equal?' will return, otherwise is diverges on
cyclic inputs.

I expect to implement the R6RS `equal?' in the near future.


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