yourInferredJvmTypeThatReferencesXDecimalLiteral.members += xDecimalLiteralReference.toField("decimal", typeof(Double))

public class DomainmodelRuntimeModule extends AbstractDomainmodelRuntimeModule {
	
	@Override
	public Class<? extends IValueConverterService> bindIValueConverterService() {
		return DomainmodelValueConverterService.class;
	}
	
	@Override
	public Class<? extends ITypeProvider> bindITypeProvider() {
		return DomainModelTypeProvider.class;
	}
	
	public Class<? extends XbaseCompiler> bindXbaseCompiler() {
		return DomainModelCompiler.class;
	}
	
}

@Singleton
public class DomainModelTypeProvider extends XbaseTypeProvider {
	
	@Override
	protected JvmTypeReference type(XExpression expression, JvmTypeReference rawExpectation, boolean rawType) {
		if (expression instanceof DecimalLiteral) {
			return _type((DecimalLiteral) expression, rawExpectation, rawType);
		}
		return super.type(expression, rawExpectation, rawType);
	}
	
	protected JvmTypeReference _type(DecimalLiteral literal, JvmTypeReference rawExpectation, boolean rawType) {
		return getTypeReferences().getTypeForName(Double.class, 
                literal); 
	}

}

 */
public class DomainModelCompiler extends XbaseCompiler {

	protected void _toJavaExpression(DecimalLiteral expr, IAppendable b) {
		b.append(expr.getIntPart() + "." + expr.getDecimalPart());
	}

	protected void _toJavaStatement(DecimalLiteral expr, IAppendable b, boolean isReferenced) {
		generateComment(expr, b, isReferenced);
	}

}

@Singleton
public class UclExtensionClassNameProvider extends ExtensionClassNameProvider {

	@Override
	protected Collection<String> computeLiteralClassNames() {
		Collection<String> result = super.computeLiteralClassNames();

		result.add(DoubleLiteral.class.getName());
		
		return result;
	}
	
	@Override
	protected Multimap<Class<?>, Class<?>> simpleComputeExtensionClasses() {
		Multimap<Class<?>, Class<?>> extensions = super.simpleComputeExtensionClasses();
		
		extensions.put(Double.class, MathExtensions.class);
		
		return extensions;
	}
}

	public Class<? extends ExtensionClassNameProvider> bindExtensionClassNameProvider() {
		return UclExtensionClassNameProvider.class;
	}

public class MathExtensions {
	
	public static Double operator_plus(Double x, Double y) {
		return x + y;
	}
	
	public static Double operator_minus(Double x, Double y) {
		return x - y;
	}

	public static Double operator_multiply(Double x, Double y) {
		return x * y;
	}
	
	public static Double operator_divide(Double x, Double y) {
		return x / y;
	}
}