Implemented compilation finished events

src/build/Function.go

@@ -20,6 +20,7 @@ type Function struct {
 
 // Compile turns a function into machine code.
 func (f *Function) Compile() {
+	defer close(f.finished)
 	f.assembler.Label(f.Name)
 	f.err = f.CompileTokens(f.Body)
 	f.assembler.Return()
@@ -124,6 +125,11 @@ func (f *Function) String() string {
 	return f.Name
 }
 
+// Wait will block until the compilation finishes.
+func (f *Function) Wait() {
+	<-f.finished
+}
+
 // identifierExists returns true if the identifier has been defined.
 func (f *Function) identifierExists(name string) bool {
 	_, exists := f.variables[name]