Change static semantics

Changing the static semantics

Now we will change the static semantics of the language. Open the main Statix file helloworld/src/main.stx Statix is a meta-language for defining the static semantics of your language, which includes type checking.

First we will update the Statix specification to handle the new language constructs. Replace the programOk(_). line with programOk(Program(parts)) :- partsOk(parts)., meaning that we accept programs consisting of parts, as long as their parts are ok. As a silly rule, we will add a warning to all instances of world in the program. Add the following code to the end of the Statix definition:

  partOk : Part
  partOk(Hello()).
  partOk(World()) :- try { false } | warning $[World!].
  partsOk maps partOk(list(*))

This adds a partOk rule that lets all Hello() parts pass, but will add a warning to all World() parts. partsOk goes over a list of parts and applies partOk.

src/main.stx full contents

module main

imports

  signatures/start-sig

rules

  programOk : Start
  programOk(Program(parts)) :- partsOk(parts).

  partOk : Part
  partOk(Hello()).
  partOk(World()) :- try { false } | warning $[World!].
  partsOk maps partOk(list(*))

Build the project, and a warning marker should appear under all instances of world in the example program.