gistfile1.hs

mul_n_sum :: String -> Int
mul_n_sum str = result
    where
    result = sum value_of_lines
    value_of_lines = [ field1 * field2 | [field1, field2] <- field_lines ]
    field_lines = [ [read txt1, read txt2] | [txt1, txt2] <- txt_lines ]
    txt_lines = [ words line | line <- lines str ]