Resource routing methods -- what am I missing?

Alright, I've been doing map.resources routing for a while now, so
whatever I'm missing must be something stupid and obvious... Anyone
care to help me out?

Call rake routes to see all the routes you have declared. That usually
makes it obvious what the problem is.

Right here, in white on black:

{:controller=>"snippets", :action=>"show"}

so, given that ... it's most definitely
algorithm_snippet_url(@algorithm, @snippet) ... right?

Yes. Are you running on latest edge? I can't remember how this worked
on 1.2.x.