Calculate my working hours from a .hours file. Comparison of Python and Haskell.

hours.hs

-- Read in an hours file and print the total hours.
-- Hours file format:
-- Desc\tDate\tStartTime-EndTime
import System.Environment
import Data.List.Split

-- Return milliseconds
get_milliseconds :: [String] -> Double
get_milliseconds xs = hours + minutes
	where
		hours = (read (xs !! 0) :: Double) * 60 * 60 * 1000
		minutes = (read (xs !! 1) :: Double) * 60 * 1000

-- Time format: HH:MM (24H)
time_difference :: String -> String -> Double
time_difference start end = (end_milli - start_milli) / 1000.0 / 60.0 / 60.0
	where
		start_milli = get_milliseconds (splitOn ":" start)
		end_milli = get_milliseconds (splitOn ":" end)

-- Recursively get every line, split it up, and figure out the total
calculate_total :: [String] -> Double
calculate_total [] = 0
calculate_total (x:xs) = (time_difference start end) + (calculate_total xs)
	where
		military_time = splitOn " " ((splitOn "\t" x) !! 2)
		start = military_time !! 0
		end = military_time !! 2

-- Determine if a line is not a comment
not_comment :: String -> Bool
not_comment str
	| str !! 0 == '/' && str !! 1 == '/' = False
	| otherwise = True

main = do
	args <- getArgs
	content <- readFile (args !! 0)
	let linesOfFiles = lines content
	putStrLn $ show (calculate_total (filter not_comment linesOfFiles))

hours.py

# Read in an hours file and print the total hours.
# Hours file format:
# Desc\tDate\tStartTime-EndTime
import sys

# Time format: HH:MM (24H)
def time_difference(start, end):
	end = end.split(":")
	start = start.split(":")
	end_milli = int(end[0])*60*60*1000
	end_milli += int(end[1])*60*1000
	start_milli = int(start[0])*60*60*1000
	start_milli += int(start[1])*60*1000
	diff = end_milli - start_milli
	diff = diff / 1000 / 60 / 60 
	return diff	


with open(sys.argv[1]) as fh:
	lines = fh.readlines()

total = 0.0

for line in lines:
	if(line[0] == '/' and line[1] == '/'):
		continue
	data = line.split("\t")
	time = data[2].split(" ")	
	diff = time_difference(time[0], time[2]) #time[1] is a hyphen(-)
	print(diff)
	total += diff

print(total)