[plt-scheme] append-map examples

I always assumed that using lists as trees/sets/maps was fairly idiomatic Scheme when prototyping / dealing with small datasets.

> Subject: Re: [plt-scheme] append-map examples
> From: matthias at ccs.neu.edu
> Date: Fri, 9 Apr 2010 22:49:29 -0400
> CC: skeptic2000 at hotmail.com; plt-scheme at list.cs.brown.edu
> To: ryanc at ccs.neu.edu
> 
> 
> Dan Friedman once shared a rule with me: when you use append-map, you are using the wrong data representation. 
> 
> Examples: 
> 
> 
> On Apr 9, 2010, at 10:40 PM, Ryan Culpepper wrote:
> 
> > Skeptic . wrote:
> >> Hi,
> >> Does someone knows canonical/pedagogical exemples of append-map except other than flatten ?
> > 
> > Collect a list of all the X in a Y.
> > 
> > eg, the list of free variables in a lambda term
> 
> Free variables come in sets, not lists. 
> 
> 
> > eg, the list of links in a web page (as xexpr or sxml)
> 
> Ditto. 
> 
> 
 		 	   		  
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