Documentation

Monaco Editor Features

The code editor is powered by Monaco (the same editor used in VS Code) with custom CQL syntax highlighting using the Monarch tokenizer.

Syntax Highlighting

• Keywords: library, define, context, using, include
• Types: Boolean, Integer, Decimal, DateTime, Interval
• FHIR Resources: Patient, Condition, Encounter, Observation
• Built-in Functions: AgeInYears, Count, Exists, Now, Today
• Date Literals: @2024-01-01, @T12:00:00

Editor Themes

Toggle between Clinical Dark and Clinical Light themes using the theme button.

Live Compilation Status

The status bar shows real-time compilation status, error count, warning count, and compilation time.

No-Code CQL Creation

The Visual Query Builder lets you create CQL measures without writing code. Build queries by selecting FHIR resources and defining conditions.

Supported FHIR Resources

Building Queries

1. Select the FHIR resources you need (click badges to toggle)
2. Add rules using the "+ Rule" button
3. Choose field, operator, and value for each rule
4. Group rules with AND/OR combinators
5. Preview the generated CQL in real-time
6. Click "Apply to Code Editor" to use the generated CQL

Operators

• =, != - Equality comparison
• <, >, <=, >= - Numeric/date comparison
• in - Value set membership
• during - During measurement period
• is null, is not null - Null checks
• ~ - CQL equivalence for CodeableConcept

CQL Validation

Click "Validate CQL" to check your code for syntax errors. The validator performs:

• Syntax validation (parentheses, brackets matching)
• Keyword and structure validation
• FHIR path expression validation
• Value set reference checking

ELM Compilation

Click "Compile to ELM" to translate your CQL to Expression Logical Model (ELM), the executable format used by CQL engines.

Translation Service

Compilation uses the CQL Translation Service. Multiple public endpoints are tried automatically with fallback. For production use, consider self-hosting:

• Railway.app: ~$5/month
• Render: Free tier available
• Docker: docker run -p 8080:8080 cqframework/cql-translation-service

Auto-Fix

If validation finds errors, click "Auto-Fix Errors with AI" to automatically correct common issues like unbalanced parentheses, incorrect syntax, and type mismatches.

Test Panel

The Test Panel (bottom-right button) lets you run your CQL against sample patient data to verify measure logic.

Test Cases

• Create: Build test cases with the Patient Builder
• Import: Load FHIR Bundles from JSON files
• Export: Save test cases for sharing
• Duplicate: Clone existing test cases

Patient Builder

Create test patients with:

• Demographics (name, birth date, gender)
• Conditions with SNOMED codes
• Medications with RxNorm codes
• Encounters with dates and types

Expected Results

Define expected values for expressions to automatically validate test results. Failed assertions are highlighted in red.

Synthea Test Data

Generate realistic synthetic patient data with Synthea. Configure population size, state, and disease modules in the Synthea panel.

Download Options

CQL File (.cql)

Download the raw CQL source code for use in other tools.

ELM JSON (.json)

Download the compiled ELM for execution by CQL engines.

FHIR Bundle

Download a complete FHIR Bundle containing:

• Library Resource: CQL and ELM content (base64 encoded)
• Measure Resource: Population definitions and scoring
• Related Artifacts: Value set references

FHIR Library Structure

{
  "resourceType": "Library",
  "type": { "coding": [{ "code": "logic-library" }] },
  "content": [
    { "contentType": "text/cql", "data": "<base64>" },
    { "contentType": "application/elm+json", "data": "<base64>" }
  ]
}

Value Set Authority Center

Search and import value sets from the NLM Value Set Authority Center (VSAC).

Searching Value Sets

1. Enter search terms in the VSAC Search panel
2. Browse results with OIDs and descriptions
3. Click to add value sets to your measure

API Key

For production use, obtain a UMLS API key from NLM UTS.

Common Value Sets