Installation

Requirements

• Node.js >= 20
• TypeScript >= 5.0
• A package manager: npm, yarn, or pnpm

Install the Core Packages

For most projects, you need the core query builder and the runtime executor:

npm install @fhir-dsl/core @fhir-dsl/runtime

Or with pnpm:

pnpm add @fhir-dsl/core @fhir-dsl/runtime

Or with yarn:

yarn add @fhir-dsl/core @fhir-dsl/runtime

Install the CLI

The CLI generates TypeScript types from FHIR StructureDefinitions. Install it as a dev dependency:

npm install -D @fhir-dsl/cli

Or run it directly with npx:

npx @fhir-dsl/cli generate --version r4 --out ./src/fhir

Package Overview

Package	When to Install
@fhir-dsl/core	Always -- this is the query builder
@fhir-dsl/runtime	Always -- provides the HTTP executor
@fhir-dsl/cli	Dev dependency -- generates types for your project
@fhir-dsl/types	Automatically installed as a dependency of @fhir-dsl/core
@fhir-dsl/fhirpath	Optional -- for type-safe FHIRPath expression building
@fhir-dsl/generator	Only if building custom tooling on top of the generator
@fhir-dsl/utils	Only if building custom tooling

TypeScript Configuration

fhir-dsl requires strict mode enabled in your tsconfig.json for full type safety:

{
  "compilerOptions": {
    "strict": true,
    "target": "ES2020",
    "module": "ESNext",
    "moduleResolution": "bundler"
  }
}

tip

Without strict: true, optional properties won't be properly narrowed and some type guards won't work as expected.

Next Steps

Once installed, generate your types and start querying.