[netvl]

After Java’s JSR-310 almost any other API in almost any other language looks broken or insufficient. Threeten’s modeling of different time types seems so powerful and natural - specifically, it has Instant (which is literally a nanosecond-precision UNIX epoch timestamp), then it has ZonedDateTime/OffsetDateTime, which are full timestamps with time zone or offset information, and LocalDateTime/LocalDate/LocalTime, which are basically these “naive” timestamps from Python. These are all different types, with well-defined conversion methods between them, so you can’t easily use an inappropriate type.

My personally most hated piece of date-related API is Go’s formatting API, with its asinine number-based patterns instead of something reasonable and conventional like strftime-like or Java-like symbols. What’s especially maddening in it is that it is so US-centric, with month coming before day in these number patterns, which does not follow unit size increase or decrease sequence.

[vsnf]

> What’s especially maddening in it is that it is so US-centric, with month coming before day in these number patterns,

Whether this particular bit of design is good or not, you'll certainly be hard pressed to find someone who has a reasonable argument in favor of the absurdity that is the Go date-time format string.

> 2006-01-02 (aka 'yyyy-MM-dd')

> January 02, 2006 (aka 'MMMM dd, yyyy')

> Jan-06 (aka 'MMM-yy')

> Monday (aka 'EEEE')

It's insanity start to finish and it boggles the mind how it was ever accepted in the language spec.