FHIR Mapping Language (FML), published by HL7 International / FHIR Infrastructure. This guide is not an authorized publication; it is the continuous build for version 0.1.0 built by the FHIR (HL7® FHIR® Standard) CI Build. This version is based on the current content of https://github.com/HL7/mapping-language-ig/ and changes regularly. See the Directory of published versions

StructureMap:

Example demonstrating the cast transform for type conversion

/// url = 'http://hl7.org/fhir/uv/mapping-language/StructureMap/TransformCast'
/// name = 'TransformCast'
/// status = 'active'
/// description = 'Example demonstrating the cast transform for type conversion'

uses "http://hl7.org/fhir/StructureDefinition/Basic" as source
uses "http://hl7.org/fhir/StructureDefinition/Basic" as target

group TransformCast(source src : Basic, target tgt : Basic) {
  src.id as v -> tgt.id = cast(v, 'string') "r1";
}