$ brew install ack
$ ack --version
Create ~/.ackrc (Below is my ackrc example, modify as you see fit)
# Options
--smart-case
--sort-files
# Exclusions
--ignore-file=is:tags
--ignore-dir=is:log
--ignore-dir=is:vendor
--ignore-dir=is:coverage
--ignore-dir=is:target
--ignore-dir=is:build
And go wild
$ ack --help-types
$ ack <string_to_find> --type ruby