Haskell parse time duration from string into DiffTime

Question

I'm trying to parse and do operations on timestamps such as this one:

"01:46:22,041"

which stands for: 1 hour, 46 minutes, 22 seconds and 41 milliseconds.

I don't really know where to begin here. The existing datatypes all seem to include a date. In my case, I only need to add/substract from the timestamp and then print it out in the same format.

I obviously don't want to write my own calculator if there's one built in. Is there any standard way to tackle this in Haskell?

Answer 1

Use Data.Time.Clock.DiffTime. To parse and format use the functions in Data.Time.Format.

Example:

import Data.Time
xyz :: String -> Maybe DiffTime
xyz x = parseTimeM True defaultTimeLocale "%H:%M:%S" x