Support FHIRPath 3.0 STU 3

[delcroip]

Is there a plan to support the function mentioned there ? https://build.fhir.org/ig/HL7/FHIRPath/en/changes.html

thanks in advance

I asked an LLM to describe what it means:

Description

Background

The official FHIRPath 3.0.0 STU 3 has been released with a significant number of new functions, improved semantics, and clarifications.

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Goals

• Achieve high conformance with FHIRPath 3.0.0 STU 3
• Pass (or clearly document) the updated official fhir-test-cases
• Maintain backward compatibility with existing 2.x behavior where possible
• Update documentation and conformance table

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Key Changes to Implement (from official changelog)

New Functions

• coalesce()
• sort()
• repeatAll()
• defineVariable()
• matchesFull()
• indexOf(), lastIndexOf()
• comparable()
• pathname()
• Aggregate: sum(), min(), max(), avg()
• Date/time extractors: yearOf(), monthOf(), dayOf(), hourOf(), minuteOf(), secondOf(), millisecondOf(), timezoneOffsetOf(), dateOf(), timeOf()
• Boundary/precision: lowBoundary(), highBoundary(), precision()

Language / Type System

• Long (integer64) literal with required L suffix
• Constructor syntax support (System.String(...), etc.)
• combine(preserveOrder) overload
• Case-sensitivity options for regex functions (matches, replaceMatches, etc.)
• Date/time subtraction improvements

Clarifications & Behavior Changes

• Singleton evaluation rules
• iif() lazy evaluation
• Equality & comparison semantics
• Quantity / UCUM handling
• Many example corrections

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Proposed Implementation Plan

1. Grammar & Parser – Update FHIRPath.g4 and regenerate ANTLR artifacts (Long literal + constructor syntax).
2. Core Functions – Implement by priority (see below).
3. Type System – Add full Long support.
4. Testing – Integrate latest fhir-test-cases and update conformance table.
5. Documentation & Release – Update README, changelog, and bump version.

Priority Order

1. Grammar + Long literal + constructor syntax
2. coalesce, sort, aggregates (sum/min/max/avg)
3. Date extractors + lowBoundary/highBoundary/precision
4. String/index functions + repeatAll/combine
5. defineVariable, comparable, pathname
6. All clarifications and test fixes

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Acceptance Criteria

• All new 3.0 functions implemented (or explicitly marked as TODO in conformance table)
• Conformance table updated with current status
• No regression in existing Normative tests
• README clearly states FHIRPath 3.0.0 STU 3 support level
• New tests added for major features