On 2018-09-17 12:01 AM, Tobias Dammers wrote:

… you can convert unix timestamps to some "local time without timezone info" data structure (e.g. LocalTime); whether you assume UTC or any timezone becomes relevant when you want to convert that data structure into a data structure that does contain timezone info explicitly (like ZonedTime) or implicitly (like UTCTime).

I don't think this is possible. If you want to measure seconds since 1970-01-01 00:00:00 local time (which may actually be 1969 in UTC) you have to know the timezone at the start (ie in 1970) and at the end (ie after the seconds have elapsed). That requires knowing whether DST applies at either end, and whether the location was rezoned during the intervening time. This requires IO and the conversion from seconds is no longer a pure operation.

IHMO, the only sane way to interpret seconds-since-the-epoch is using UTC.