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If you could write a programming language how would it be?

Lucas Frota on January 06, 2018

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nektro profile image
Meghan (she/her) •

I’ve thought about this a lot, and writing a compiler is actually one of the projects on my GitHub but I’ve realized recently that my dream language is actually just JavaScript with 2 changes.

1) Module only operation, nothing in global scope except primitives (String, Number, Array, Symbol, Object), every other API must me called via import
2) and the addition of a ‘use native’; directive that could be used to make JS fully compliable within certain rules. Ie: forced jshint comments on all functions to define parameter types, no setting a variable to a type other than its initial, and no dynamic property setting unless in constructor

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Bob van Hoove •

no setting a variable to a type other than its initial

+1 for type safe javascript w/o transpiling, I'd like that a lot

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Eljay-Adobe •

... no setting a variable to a type other than its initial ...

At a previous company, they developed a language called TypeScript that transpiles into JavaScript (ES3 or ES5). (Sorry Bob van Hoove... yep, transpiles.)

One of its features was static type checking, which went a long way to eliminate a large category of bugs. The folks at Google liked it so much, that they used it for Angular 2.

I worked on a very large project that used TypeScript throughout, and it was pretty nice. (TypeScript also made available a lot of ES6 features, way before ES6 was ready for primetime. So that was very cool too, at that time.)

Now we have ES6 at our disposal, so at least one big feature that TypeScript still provides is the static type checking.

Maybe some future version of JavaScript (ECMA-262 and ISO/IEC 16262) will add that into the core language.

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nektro profile image
Meghan (she/her) •

TypeScript is very cool and I especially like their idea of automatic constructor property assignment but unfortunately, TS isn't supported natively and must be transpiled :(

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orkon profile image
Alex Rudenko •

You forgot 64bit integers and, perhaps, proper integers in general :-D

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nektro profile image
Meghan (she/her) • • Edited

All numbers in JavaScript are automatically 64 bit floating-point numbers.
Source: ECMAScript 262 § The Number Type

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mortoray profile image
edA‑qa mort‑ora‑y •

It'd be like this :)

The biggest challenge, besides actually writing a compiler, is sorting through the intense dogmas in the programming community and figuring out what features are really desired.

I'm taking the approach of top-level down: coming up with the code I want to see and then determining which features will make that happen. Of course, there's a lot of compromise, since a fully modern language takes a long time to develop, but needs a lot of people helping.

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Bob van Hoove • • Edited

I'm not a language expert. But I could think of a feature that would work in C# / Java. I really don't like DI boilerplate code. So rather than writing:

public class Composed
{
    private DepA a;
    private DepB b;
    private DepC c;
    private DepD d;
    private DepE e;

    // I usually move the constructor to the bottom since
    // taking dependencies is the least interesting thing
    // my class does

    public Composed(DepA a, DepB b, DepC c, DepD d, DepE e)
    {
        // hooray for throw expressions, saving us 5 boring LOC :)

        this.a = a ?? throw new ArgumentNullException(nameof(a));
        this.b = b ?? throw new ArgumentNullException(nameof(b));
        this.c = c ?? throw new ArgumentNullException(nameof(c));
        this.d = d ?? throw new ArgumentNullException(nameof(d));
        this.e = e ?? throw new ArgumentNullException(nameof(e));
    }
}

I'd like to write

public class Composed
{
    // Constructor is inferred
    private injected DepA a;
    private injected DepB b;
    private injected DepC c;
    private injected DepD d;
    private injected DepE e;

    //
    // Stuff that matters right at the beginning, no boilerplate
    //
}

I may be naïve though:

  • This implies that you cannot take 2 dependencies of the same type using the fictuous injected keyword. The new tuple features could be of help.
  • If you have 5 or more constructor arguments maybe it's time recompose.
  • Perhaps I should give F# a go?
  • Now you might need a method for other stuff you want to do during construction

EDIT: Extra con argument, spelling

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mortoray profile image
edA‑qa mort‑ora‑y •

Ultimately all programmer's desire meta-programming capabilities. It's unfortunate that most new languages tend to rail against the idea (for example, when's the last time you've seen a Macro preprocessor since C/C++?)

I believe there is a draft for even more extended meta-programming for C++.

I hate redundancy, thus will be looking for all ways to get rid of it in Leaf. I like your example since it points out how meta-programming can be used to add clarity to your code. injected says a lot more about intent than does a constructor parameter.

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Alain Van Hout •

In Java with Spring, you already get this via @Autowired/@Inject, though that's of course a framework-level rather than a language-level feature. (this mindset is a big reason why I favour field injection over constructor injection)

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Bob van Hoove •

I think this would be possible in .Net if you use attributes on the properties.

What I like about constructor injection is that the dependency requirement is by 'contract' regardless of how you compose. Even without a DI framework there's still only 1 way to compose the object.

I can see how field injection could be more practical. I should ask my Java colleagues about Dependency Injection in Spring :)

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Alain Van Hout • • Edited

Also in the Java world, people with strong views on DI tend to favour constructor injection, generally because it's more 'pure' (i.e. not bound to a DI framework and manually usable).

I see these kinds of fields as a special kind of field (similar to in your post) and as such see the use of the constructor as pointless boilerplate at best and a loss of pertinent semantics at worst).

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Tobias Salzmann •

To me, it seems that what you really want is boilerplate free constructors. Even on the JVM, there are already some languages that do this quite well, Kotlin and Scala.

class Composed @injected() (
  private val a: DepA,
  private val b: DepB,
) {
 ...
}

You could make the injected annotation a keyword in your language. That way, you would still clearly communicate what a dependency is, and keep the class usable without dependency injection (in tests, for example)

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Eljay-Adobe • • Edited

I've tried. It's hard.

Fortunately, there are several successful languages that I find to be outstanding.

  • D (v2.x), a better C++ than C++
  • Python (v3.x), everything — including the kitchen sink — scripting language
  • F# (v4.1), basically OCaml for .NET, which puts functional programming as the front-and-center foremost idiom
  • Lua (v5.x), powerful, lightweight, embeddable scripting language
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Lucas Frota •

I have also tried to create my own programming language but it is being much harder than I thought it would be, I mean it doesn't even work properly for now, here is the repository if if you're curious
github.com/Lucasfrota/lazy_cat_lang