Haskell

nonconstant snippets syntaxes catamorphism misphrased noniterative mapreduce alang zipwith typeclasses composable namespace xmonad publically comprehensions generics instated unassessed fixedpoint monads corecursion redexes foldl parallelizable epolyglot sigplan eiffel scala clojure monads enumfromto systemverilog pointfree corecursion cryptol

This thread is now about google searches which return /prog/ as the top result, or more generally the first page.

http://www.google.co.uk/search?q=valid+perl+code