> I solve and write a lot of puzzlehunts, and I wanted a better programming language to use to search word lists for words satisfying unusual constraints, such as, “Find all ten-letter words that contain each of the letters A, B, and C exactly once and that have the ninth letter K.” So... Perl?
sls '^........k.$' .\wordlist.txt -raw |where { $W=$_;
('a','b','c' |where
{ $W.Contains($_) -and $W.IndexOf($_) -eq $W.LastIndexOf($_) }
).Count -eq 3 }