if(condition) {
  println(1)
}
else {
  println(2)
}

MyIf.run(condition,
  new Runnable() {
    public void run() {
      println(1);
    }
  }, 
  new Runnable() {
    public void run() {
      println(2);
    }
  }
);

if(...) {
  println(this.a)
}
else {
  this.a = 1
}

grammar org.xtext.example.mydsl3.MyDsl with org.eclipse.xtext.xbase.Xbase

generate myDsl "http://www.xtext.org/example/mydsl3/MyDsl"

import "http://www.eclipse.org/xtext/xbase/Xbase" as xbase

Model:
	body=MyXBlockExpression;
	
MyXBlockExpression returns xbase::XExpression: 
	{xbase::XBlockExpression}
	'{'
		(expressions+=MyXIfExpression ';'?)
	'}';	
	
MyXIfExpression returns xbase::XExpression:
	{xbase::XIfExpression}
	'if' '(' if=XExpression ')'
	then=XClosureX
	(=>'else' else=XClosureX)?;

	
XClosureX returns xbase::XExpression:
	{xbase::XClosure}
	explicitSyntax?="{"expression=XExpressionInClosure"}";

class MyDslJvmModelInferrer extends AbstractModelInferrer {
	@Inject extension JvmTypesBuilder

   	def dispatch void infer(Model element, IJvmDeclaredTypeAcceptor acceptor, boolean isPreIndexingPhase) {
   		acceptor.accept(element.toClass("my.company.greeting.MyGreetings"))
   			.initializeLater([
   				
   					members += element.toMethod("doSomething", element.newTypeRef(Runnable)) [
   						body = element.body
   					]
   				
   			])
   	}
}