HN user
The main problem is probably creating and traversing the strings, although I have not benchmarked it. This version https://gist.github.com/Codas/894694eea247aaacf35f runs about 4 times faster than the python version on my machine.
It does use some libraries that are not in the haskell platform though.
There is also postgrest, providing a REST API for postgresql databases.
The rust compiler itself would certainly not be the best resource, but I thing servo[1] would do just fine. Also, you can just look at some rust repositories[2] on github.
In addition to those jbeja mentioned, there is also fiplr[1], somewhat in the spirit of ctrl-p, command-t etc. for vim.
One favorite tweak of mine for file finders like this in general: rewrite the dir listing to use "git ls-files -co --exclude-standard". This obviously only works in git projects (similar commands exist for mercurial I think), but is really fast and most of the time is exactly what I want.
You might also want to take a look at the ergodox: http://ergodox.org/ It's not so easy to buy as its just a DIY project. Massdrop organizes some group buys [1], next one should be due anytime this year.
[1] https://www.massdrop.com/buy/ergodox unfortunately, requires an account even to see the offers