Flockenzeit: Nix Time Manipulation

Using this library

All the user-facing functions are contained in the lib output (or in default.nix, if you're not using flakes).

⚠️ A note about timezones

This does not handle timezones, because I want to keep my sanity. All the times are in UTC.

Functions

splitSecondsSinceEpoch

Splits the number of seconds since UNIX epoch (00:00:00 UTC on 1970-01-01) into date-esque parts. The first argument allows you to specify a locale (which must contain ordered weekday names, month names, and a function to format the datetime). The default locale is C, provided as locales.C, which means you can just pass an empty attribute set as the first argument and not worry about it.

Parts which are purely numeric (e.g. Y (year), H (hour), etc) are kept as integers, so you'll have to pad them yourself (see pad). Composite parts (e.g. T (time)) are strings. Parts which are locale-dependent are taken from the specified locale.

For meaning of all the parts, consult man date.

Example:

nix-repl> with splitSecondsSinceEpoch {} __currentTime; "It's a nice ${A} out today, isn't it? What a lovely ${B} day in ${toString Y}."
"It's a nice Friday out today, isn't it? What a lovely December day in 2022."

ISO-8601

Presents time in the ISO 8601 format, like 2009-02-13T23:31:30.000000000Z .

Example:

nix-repl> ISO-8601 __currentTime
"2022-12-16T08:32:18.000000000Z"

RFC-5322

Presents time in RFC 5322 (email) format, like Mon, 14 Aug 2006 02:34:56 +0000

Example:

nix-repl> RFC-5322 __currentTime
"Fri, 16 Dec 2022 10:02:38 +0000"

RFC-3339

Presents time in RFC 3339 format, like 2006-08-14 02:34:56+00:00

Example:

nix-repl> RFC-3339 __currentTime
"2022-12-16 10:04:48+00:00"

pad

pad takes a padding symbol, the desired length, and the string. If the string is shorter than the desired length, left-pads it with the padding symbol until it is of the desired length.

pad0 is simply pad "0".

Example:

nix-repl> pad " " 2 4
" 4"

nix-repl> pad "0" 4 123
"0123"

nix-repl> pad0 4 123
"0123"