Implementing Slices

[holtwick]

You wrote about implementation of Slices:

"Slices would indeed be neat. Any suggestion on how this could be implemented? If you want to experiment, you want to create a new AST mutator (copy-paste one in lib/ast-mutators.js), enable it in the "compile" function (lib/index.js) and then hack in the support into the AST mutator. This provides a very flexible workflow as you can inspect the AST without, while and after your mutator applied."

I had a look at it and found out that we first need to modify the parser.js to get an AST with the needed information. I think you know the code better than I do, but I think we need something here:

function subscripts(expr, allow_calls) {
    // ...
    if (is("punc", "[")) {
      next();
      return subscripts(as("sub", expr, prog1(expression, curry(expect, "]"))), allow_calls);
    }

After having the parser recognizing these cases:

object[expr:expr]
object[expr:]
object[:expr]
object[:]

or at least the first one, I could try to create the AST mutator. Maybe you could give me some help here? Thanks.

[rsms]

I've now implemented this in the core as well as provided implementation for Array types. Check out and test https://github.com/rsms/move/commit/d47f880c4b7c6b29709a60fbb3a1edd98b3ddba8 (latest master as of writing this)

[rsms]

Well, reading/extracting slices from text is also implemented in a way, although we got it "for free". E.g.

print "hello"[1:3]  # --> "el"

[rsms]

Implemented, tested and documented.

[holtwick]

Awesome. Thanks! Here a little addition https://github.com/holtwick/move/commit/9e117dcfb4e130a71c1395ae201ac90f907a900a