Timezone Library

IANA timezone name constants for use with TIMEZONE IS declarations and DateTime constructors. Maps common timezone abbreviations to their full IANA names. Can be imported into L4 files with IMPORT timezone.

Location

jl4-core/libraries/timezone.l4

Features

• Named constants for common timezone abbreviations
• Automatic DST handling (EST and EDT map to same IANA zone)
• Coverage: Americas, Europe, Asia-Pacific, Universal

DST Handling

Standard and daylight-saving abbreviations map to the same IANA zone. The underlying timezone database handles DST transitions automatically based on the actual date:

IMPORT timezone

-- Both resolve to "America/New_York"
-- DST is determined by the date, not the abbreviation
#ASSERT EST EQUALS EDT

Available Constants

Americas:

Constant	IANA Zone
EST, EDT	America/New_York
CST, CDT	America/Chicago
MST, MDT	America/Denver
PST, PDT	America/Los_Angeles

Europe:

Constant	IANA Zone
GMT, BST	Europe/London
CET, CEST	Europe/Berlin
EET, EEST	Europe/Helsinki

Asia-Pacific:

Constant	IANA Zone
IST	Asia/Kolkata
SGT	Asia/Singapore
HKT	Asia/Hong_Kong
JST	Asia/Tokyo
KST	Asia/Seoul
AEST, AEDT	Australia/Sydney
NZST, NZDT	Pacific/Auckland

Universal:

Constant	IANA Zone
UTC	Etc/UTC

Usage with TIMEZONE IS

IMPORT timezone

TIMEZONE IS SGT  -- sets document timezone to "Asia/Singapore"

You can also use IANA strings directly without importing this library:

TIMEZONE IS "Asia/Singapore"

Example: Timezone Constants

-- Timezone Example: IANA timezone constants
IMPORT timezone

-- Set document timezone using a constant
TIMEZONE IS EST

-- Verify the resolved IANA name
DECIDE `document timezone` IS TIMEZONE
#EVAL `document timezone`  -- "America/New_York"

-- Timezone constants resolve to IANA strings
#EVAL EST  -- "America/New_York"
#EVAL PST  -- "America/Los_Angeles"
#EVAL SGT  -- "Asia/Singapore"
#EVAL UTC  -- "Etc/UTC"

-- EST and EDT map to the same zone (DST handled automatically)
#ASSERT EST EQUALS EDT

See timezone.l4 source for all constants.