[plt-scheme] Bug in pattern matching with failure procedures and multiple return values

From: Thomas Chust (chust at web.de)
Date: Fri Nov 14 14:47:11 EST 2008


I ran into a problem when using failure procedures in a match expression
that was intended to return multiple values. Here is a simplified example:

% mzscheme
Welcome to MzScheme v4.1.2 [3m], Copyright (c) 2004-2008 PLT Scheme Inc.
> (match 'foo [_ (=> skip) (skip)] [_ (values 1 2)])
context expected 1 value, received 2 values: 1 2

The error only occurs if the declared failure procedure has actually
been called, which feels very much like a bug :-(


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