STWL: Strongly Typed Web Language

Proposal: A strongly typed, programming language that compiles to JavaScript, with the following features:

• Error unions: Error!string
• Optional values: ?string
• scoped blocks
• exhaustive pattern matching
• "unreachable" keyword
• built-in reactivity system (using signals?)

Syntax example (very early proposal, might change):

  //imports work just as in ES6
  import { func1, func2, func3 as funFunc } from './MyCoolModule'
  import Cool from './MyCoolModule'

  // although I might add something like this in the future:
  import './MyCoolModule' as Cool // because it just reads so much nicer

  // Declarations can be constant, variable or live (a.k.a. reactive):

  // Constants can never change
  const c = 299792468 // neither type nor value will ever change
  c++ // Error! Constant values cannot change.

  const car = struct{
    tires: 4,
    engine: true
  }

  car.tires = 5 // Error! Unlike in JS, struct values cannot be changed, either

  // Variables can be changed, as long as their type stays the same:
  var vehicle = struct{
    tires: 2
    engine: true
  }
  vehicle.engine = false // no problem
  vehicle = struct{ // also fine
    tires: 2
    engine: false
  }
  vehicle = struct{ // Error! Type cannot be changed
    color: 'red'
  }

  // Live values can be changed and their changes are tracked
  live speed = 50
  track speed {
    console.log(`Driving ${speed} km/h now`)
  }
  speed++ // logs speed automatically

  speed = 'fast' // gives an error, because the type cannot change

  // Computed values are basically getters (similar to Vuejs' computed)
  computed apparentSpeed {
    // pattern matching is another useful language feature that is explained in
    // further detail later
    return match speed {
      10 -> 'walking speed'
      _ < 50 -> 'inside town, maybe'
      _ -> 'outside town, hopefully'
    }
  }