Skip to content

Instantly share code, notes, and snippets.

@jml

jml/addToKey.hs

Created August 31, 2015 17:08
Show Gist options

  • Select an option

    Learn more about clone URLs
  • Save jml/e2abbc93a227b4bc7be9 to your computer and use it in GitHub Desktop.

Select an option

Learn more about clone URLs
Save jml/e2abbc93a227b4bc7be9 to your computer and use it in GitHub Desktop.
Download ZIP
Raw
addToKey.hs
addToKey :: Ord k => k -> a -> Map k [a] -> Map k [a]
addToKey key value =
M.alter f key
where f Nothing = Just [value]
f (Just values) = Just (value:values)
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment