Type System Improvements

[gdotdesign]

This PR is an RFC for visual improvements for the code itself.

I feel like that Mint code has some visual clutter which can be resolved quite easily, but for some we need type inference.

Removing some elements helps reduce visual complexity, makes it easier to read and reason about the code, also it has the additional benefit of writing less.

Types

For functions, states, properties and computed properties the type (or return type) is required, and for me sometimes it's a burden to write them. These type definitions can be made optional.

The only downside of that is that for recursive functions and for the component records we need to calculate static type signatures and without a defined type we can use a type variable a but having a type for helps with that.

Type definitions elsewhere will still be required (arguments, provider, records, etc...)

The fun keyword

It is possible to remove the fun keyword which in hindsight is not needed.

---

Here is an example of how a component file looks now and how it can look with this PR:

global component LoadingOverlay {
  state loading : Bool = false

  style base {
    cursor: progress;
    position: fixed;
    z-index: 10000;
    bottom: 0;
    right: 0;
    left: 0;
    top: 0;
  }

  fun show : Promise(Never, Void) {
    next { loading = true }
  }

  fun hide : Promise(Never, Void) {
    next { loading = false }
  }

  fun render : Html {
    if (loading) {
      <div::base/>
    } else {
      <></>
    }
  }
}

global component LoadingOverlay {
  state loading = false

  style base {
    cursor: progress;
    position: fixed;
    z-index: 10000;
    bottom: 0;
    right: 0;
    left: 0;
    top: 0;
  }

  show {
    next { loading = true }
  }

  hide {
    next { loading = false }
  }

  render {
    if (loading) {
      <div::base/>
    } else {
      <></>
    }
  }
}

---

This PR can be merged as-is, all the tests pass, however I still plan to work on this.

The fun keyword is optional but the compiler throws a warning that it will be removed in the future and the formatter automatically removes them.

Please give your feedback and if there is anything else which you think can be removed just let me know.

[s0kil]

The Promise(Never, Void) Type is very common, this PR will make it easier.

[Namek]

I would leave fun as it is. It's easier to search for a function definition when it is prefixed.

Other than that, I would like to have an ability to restrict/write types of variables in try block.

Oh, and I love that it's all optional. Especially anonymous functions (used with mapping, filtering) can benefit from that.

[gdotdesign]

Other than that, I would like to have an ability to restrict/write types of variables in try block.

It's easy to add it as an optional thing, I can see that it could be helpful from some situations, I never needed myself it though.

I would leave fun as it is. It's easier to jump in view of I can search a function definition when it is prefixed.

I have mixed feelings here as well. GitHub need to implement some kind of polls for issues 😂

[Sija]

I would leave fun as it is. It's easier to jump in view of I can search a function definition when it is prefixed.

I have mixed feelings here as well. GitHub need to implement some kind of polls for issues 😂

@gdotdesign It's pretty easy!

Add a 👍 reaction to this comment for leaving fun or 👎 for removing it :)

[Namek]

this doesnt seem right

[gdotdesign]

Strictly speaking the parser does not need white-space between the keyword and the name of the store here.

It's because there is no tokeniser phase, the parser directly produces the AST.

[Namek]

why is it empty now?

[gdotdesign]

These tests does not execute JavaScript code, it just parses the code and type checks based on the annotations, so it does not make sense having that here.

[gdotdesign]

By popular demand the fun keyword will not be removed 🙂 and changes were reverted.

Now this PR contains the following:

• optional return type definition for functions and inline functions
• optional type definition for state, get and property
• default value for properties can now be omitted Required properties #132
• restricting type of arrays: [] of Number
• restricting type of inline JavaScripts:

`"Hello"` as String

[gdotdesign]

Two more issues has been implemented here:

• Pipe operator overhaul (can be piped into expressions instead of just calls) Pipe(?) operator explaination #228
• Record constructors Feature Request: default constructor for records #191