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Date Phrases and Set Operations

Date phrases let you combine date expressions, including multiple calendar schemes, using set and other operators. This allows you to express unions, intersections, exclusions and differences between periods expressed in differing calendar schemes all in a single phrase. The phrase is then converted to an ordered list that can be displayed or further manipulated.

A Date Phrase is made up of one or more Date Expressions combined using operators. The supported operators are:

• Range - operator .. - specifies an inclusive range of dates between two date expressions.
• Complement (NOT) - operator ! - specifies the inverse of a date expression.
• Union (OR) - operator | - combines two date expressions to include all dates from both expressions.
• Intersection (AND) - operator && - combines two date expressions to include only dates that are present in both expressions.
• Difference (XOR) operator ^^ - includes dates that are present in either of the two expressions but not in both.
• Exclusion (AND NOT) - operator \\ - removes dates from the first expression that are present in the second expression.

Notes

• Parentheses ( ... ) are supported for grouping and controlling precedence.
• All values between operators must be well-formed dates or shortcut ranges in valid hics syntax (see earlier sections).
• Other arithmetic operators may appear in future releases.

Scheme and Format Qualification

A date phrase will have a default scheme and format unless otherwise specified.

To use non-default schemes in a phrase, prefix the entry with scheme[:format]#, for example:

Example Script
@phrase.g:dmy("2025 | j:dmy# 2025")

Combines the Gregorian year 2025 and Julian year 2025.

Example Usages

// Range and union @text.g:dmy(@phrase("1 Jan 2025..10 Jan 2025 | 15 Jan 2025")) // Exclusion @text.g:dmy(@phrase("2025 && !30 Nov 2025")) // Scheme qualification @text.g:dmy(@phrase("2025 | j:dmy# 2025")) // Set subtraction @text.g:dmy(@phrase("2025 \\ Jan 2025")) // Parentheses for grouping @text.g:dmy(@phrase("(2025 | 2026) && !10 Jan 2025")) Limitations (for now) Only valid date values or shortcut ranges (not arbitrary words) are accepted. More advanced operators beyond those listed are in development/testing. Summary: Date phrases let you combine and manipulate lists or ranges of dates using familiar set operators, with parentheses for grouping. The set subtraction operator is two backslashes: \\. Each value must be a valid date expression. You can mix schemes/format using qualification; see examples above.