It's possible to do pattern matching in Scheme, though it's not standardized (AFAIK). Here are some approaches:

https://curiousprogrammer.wordpress.com/2006/12/08/pattern-m...

http://www.javaist.com/blog/2008/11/12/pattern-matching-in-s...

http://wiki.call-cc.org/eggref/3/pmatch

http://wiki.call-cc.org/man/3/Pattern%20matching.html

http://www.ccs.neu.edu/home/samth/match-ifl-full.pdf

http://download.plt-scheme.org/doc/203/html/mzlib/mzlib-Z-H-...