gigasecond: use times (not dates) for inputs and outputs about haskell

[etrepum]

With regard to daylight savings, if you're using a standard library it will almost certainly take daylight savings into account for you. This could make it hard to write the tests properly unless you normalize the test datetimes to UTC or build them from epoch seconds (which would reveal a very obvious way to solve the problem).

[kytrinyx]

In that case I suggest that let the daylight savings stuff as is.