Language Draft #43

coolaj86 · 2023-02-07T23:42:25Z

Questions

Is it possible to eliminate semicolons without creating opportunities for obscure errors?
Is it possible to eliminate either try/catch or .catch().then()?
(probably not since you can't unwind an async stack)

Guiding Principles

readability first
everything is an interface
maximize tool-assisted coding

Language Principles

smaller language, larger standard library
environment dictates use case
- single-core Browser with mostly-memcopy workers (https://brave.com/)
- single-core servers that scale horizontally (https://bun.sh/)
- low-latency document-processing systems (https://wintercg.org/)
- low-hertz microcontrollers (https://bellard.org/quickjs/)

Syntax Principles

performance over cool functional and CS concepts
(no prototypes, no inheritance, no chaining, no reduce)
minimize human brain parser complexity
(at the expense of expressiveness and the tax of verbosity)
minimize machine parser complexity (hopefully for all benefits)

Ai JitScript by Example

Type System

Duck-Typing is King! (everything is an interface)

Types are TitleCase
Types are Drafted automatically by tooling
All properties are always optional?
(because we can tell if a property exists?)

Type Drafting

Types can be inferred from correct code, and drafted automatically.

Consider this code:

var Person = module.exports;
Person.create = function(opts) {
  var p = {};

  p.name = opts.name           // required
  p.age = opts.age || null     // optional
  p.ssn = opts.ssn             // required
  p.friend = opts.friend || p  // optional
  p.fullName = function () {
    return `${p.name} ${p.last}`
  };

  return p;
}
Person.fullName = function (p) {
  return `${p.name} ${p.last}`
};

Person.create({ name: "Jack", age: 42, friend: "Jeff" });

Since the code and its execution can be entirely understood, we can draft the type based on known information:

/***
 * A person interface
 * @Person Struct
 * @name String
 * @age Number?
 * @ssn UNKNOWN           // WARN: incomplete use / conflict
 * @friend String|Person
 *
 * $version draft ef2b31  // drafted, non-authoritative
 *                        // can be updated by tooling
 */

Note: draft means that we should not use the type comment to enforce what the code should be, but rather we re-gen on code update. Anytime the code is correct and the type definition is out-of-date we can change the $version to draft to allow it to be regenerated.

var Person = {}

/***
 * @Create                        // the constructor type
 * @opts Person{                  // sub-interface definition
 *         name,
 *         age?,
 *         ssn,
 *         friend?,
 *       }
 *                                // (properties have the same type as Person)
 * returns @Person
 */
Person.create = function(opts) {
  var p = {};

  p.name = opts.name              // required
  p.age = opts.age || 0           // optional
  p.ssn = opts.ssn                // WARN: ambiguous
  p.friend = opts.friend || p     // enum

  return p;
}

Person.create({ name: "Jack", age: 42, friend: "Jeff" });

We can tell by the usage what a Person object can and can't be.

Concrete types

/***
 * A person (or person-esque) interface
 * @Person Struct            // Object, sans prototype stuff
 * @name String              // common String
 * @age  NaturalNumber|null  // 1 to MAX_SAFE_INTEGER, or null
 * @bankBalance BigInt       // can be pos, neg, or 0! (probably in pennies)
 * @friends []Person         // friend list or null
 * @favoritePet Pet|null?    // pet or null or not defined
 *
 * $version v1.0.1           // whether the type has been locked
 */

/*** @Person */
var Person = {};
Person.name = "AJ";
Person.age = 0;

To create an ad-hoc new type:

function getInterestingType() {
    /*** @KnownType */
    var knownType = { foo: "bar" }

    var newProperties = { bar: "baz" };
    var newType = Object.assign(knownType, newProperties)
}

// this is now known to be KnowType-ish + `bar` and can be checked as such.
var interestingType = getInterestingType();

If a function can throw, that's part of its type information.

 // not possible to throw
 function add() {
   var sum = 2 + 5;
   return sum;
 }

 // can throw
 function divide(a, b) {
   var quotient = a / b;
   return quotient;
 }

How should we indicate that? /** @throws */ ?

Functions

function names are camelCase

// ✅
function doStuff() {
  // statements
}

// ❌
function do_stuff() {
  // statements
}

a function expression can be assigned to a property

// ❌
var doStuff = function () {
  // ...
};

// ✅
foo.bar = function () {
  // ...
};

// ⚠️ not sure on this one, learning towards no
foo.bar(function () {
  // ...
});

// ✅ definitely okay
foo.bar(doStuff);
function doStuff() {
  // ...
})

a function can be declared after a return

function main () {
  // ⚠️ not sure on this one, learning yes
  foo.bar(doStuff);
  return;

  function doStuff() {
    // ...
  })
}

calling a function is the end of an expression (no chaining)

foo.bar.baz(); // ✅

foo.bar.baz().length; // ❌

// ⚠️ EXCEPTION we probably have to have .then().catch()
await foo.bar.baz().then().catch().then();

functions can be async (but cannot be generators)

// ✅
async function doStuff() {
   // statements
}

// ❌
function* doStuff() {
   // statements
}

return values must be used or voided (for side effects)

// ✅ used
var quux = foo.bar.baz();

// ✅ discarded
void foo.bar.baz();

async statements MUST be called with await
```
// ✅
await foo.bar.baz();
```

async expressions are valid if Promise is a valid type

// ✅
var jobs = [];
jobs.push(
    foo.bar.baz(),
);

true background tasks that can throw MUST be handled

// ✅
setImmediate(async function () {
  var result = await foo.bar.baz();
  result.catch(console.error);
});

you cannot invoke a non function

// ❌
var MyPackage = exports

(function () {
  // ...
}())

// ✅
var MyPackage = exports

void (function () {
  // ...
}())

any invocation outside of main() must be statically inspectable

// ❌
var x = makeRequest(process.env.API_TOKEN);

function main() {
  var y = doMoreStuff(x);
}

// ✅
var x = doStuff();

function main() {
  // 💪 we should know exactly what x is here
  var y = doMoreStuff(x);
}

// ⚠️ maybe?
var x = Fs.readFileSync("./thing.txt", null);

function main() {
  // 💪 we should know exactly what x is here
  var y = doMoreStuff(x);
}

there MUST NOT be whitespace the identifier (fn) and the invocation (()

// ❌ 
fn
(
  1,
  2,
  3,
)

// ✅ 
fn(
  1,
  2,
  3,
)

Special Functions

async function main() must exist for "bins"
function create() must NOT be async
async function init() MUST be async

Variables

considering var only because...

shadowing is possible

// ❌
// "string"
var age = input.value;

// "number" cannot change types!!!
age = parseInt(age, 10);

// ✅
// "string"
var age = input.value;

// "number" (shadowed)
var age = parseInt(age, 10);

constants are ALL_CAPS
```
var PI = 3.14
```

Expressions

We have several types of expressions:
- Template String Expressions
  (the same as accessor expressions for now)
- Accessor Expressions
  (access variables and properties)
- Invocation Expressions
  (accessor expression ending with a function invocation)
- Bitwise Expression
- Sum, Difference, Product, Quotient, and Exponent Expressions
- Logical Expression (between Boolean expressions)
- Boolean Expression
- Nullish Expression
All expressions MUST be captured
(EXCEPTION: functions can be voided, see Functions)
```
// ❌
void foo.bar.baz;
foo.bar.baz;
```
```
// ✅
var x = foo.bar.baz;
```

Accessors can be chained, and on new lines
(but not functions, see Functions)

// ✅
// ES-style (but prettier-supported)
var x = foo["1"]
  .bar
  .baz;
// Go-style 💪
var x = foo["1"].
  bar.
  baz;

Accessors cannot contain complex expressions

// ❌ 
var x = foo[n + 1];
var y = foo[n + 2];

// ✅ tedious but... maybe allow `+=` ?
n = n + 1
var x = foo[n]
n = n + 1
var y = foo[n]

n = bar.baz()
var z = foo[n]

var a = foo[bar.bar]

// ⚠️ I'm on the fence - this is hard to read, leaning no
var x = foo[bar.baz()];

no whitespace between arr or obj and [

// ❌ 
arr
  [
    1, // obviously no comma
  ]

// ✅
arr[
  "1" // newline allowed for compat with `prettier`
]

Strings

templates MUST ONLY contain strings and Invocation Expressions:

// ❌
var msg = `Hello ${friend[i].name}, I'm ${me.getName()}`

// ✅
var msg = `Hello ${friend[i].name}, I'm ${me.getName()}`

note: this is an argument against allowing += in sub-index:
we can create template strings we can interpolate without eval

function execTemplate(tmpl, { friend, me }) {
  var accessors = tmpl.match(/magic/g);
  // ... magic
  {
    var val = getByMagic(accessorPath, friend);
    replaceByMagic(tmpl, accessorPath, val);
  }
}

or we could have another type of expression just for
template strings that allows the simplest accessors,
but not invocations (potentially unsafe) or indexes + logic

Numbers

Some rough, not-well-thought-out ideas (Re: can division throw):

1 - NaturalNumber? (only 1 - Math.MAX_SAFE_NUMBER)
0 - BitwiseInteger (can be zero, but not negative, up to 2**32)
-1 - Integer (can be 0, or negative)
1n - BigInt
1.0 - Float

Macro System

Think of prettier - the macro parser and expander executes on save.

Arrow Expressions to Functions

// 🤮
const annoyMe = n => n + 1
// or
const annoyMe = (n) => { 
  n + 1
}

// 😉
function annoyMe(n) {
  return n + 1
}

Class Statement to Factory Function

// 🫤
class SelfLoathing {
  constructor() {
    this.name = "evil";
  }
  greet(other) {
    return `Hello ${other}, I'm ${this.name}`;
  }
}

// 😉
var SelfLoathing = {};
SelfLoathing.create = function () {
  var s = {};

  s.name = "evil";

  s.greet = function (other) {
    return `Hello ${other}, I'm ${s.name}`;       
  };

  return s;
};
// TODO how do we chose the name of `this` => `s`?
// note: either `var s = { foo: bar, baz: quux }`
//       or `var s = {}; s.foo = bar; s.baz = quux;`
//       but not `var s = { foo: bar }; s.baz = quux;`

Syntax

Keywords

These words cannot be used for standalone variable or function names, but may be used as property names.

(30) arguments, async, await, break, case, catch, const, continue, debugger, default, delete, else, export, exports, false, for, function, if, import, in, let, null, return, require , switch, throw, true, try, typeof, undefined, var, void

Idea: can we remove more without increasing pain?

(24) arguments, async, await, break, catch, continue, delete, else, export, exports, false, for, function, if, import, in, null, return, require, throw, true, try, typeof, undefined, var, void

(unused: case, debugger, default, switch, import, export, var, const)

Special Words

of
new

(Unused) Reserved Words

These words are reserved for historical reasons.

do, class, enum, eval, extends, finally, function*, implements, instanceof, interface, let, new, package, private, protected, public, static, super, this, while, with, yield, yield*

Non-Reserved Words

These words might appear to be reserved, but they aren't.

abstract, boolean, byte, char, double, final, float, goto, int, long, native, short, synchronized, throws, transient, volatile

Syntax Characters

Alphanumeric and Word Characters:

a-z
A-Z
0-9
_,

Identifiers can also contain:

$

Accessors may also use:

.
[
]
?. (which is a pair, not ? and .)
newlines (but not spaces)

Functions use:

(, )
,
{, }

Math Operations:

+ (but not ++ or += or --)
*, / (but not *=, \=, or **=)
** (like Math.pow(), but for BigInts)
%
>, <, <=, >=
=== (but not ==)

Strings:

`
"
(not ')

Logical Operators:

!
!== (but not !=)
&&
|| (and maaaaaybe ||=)
?? (⚠️ do we need that in this language?)
(ex: function ({ x = null }) { x = x ?? true })

Bitwise Operators

~
^, but not ^=
&, but not &=
|, but not |=
<<, >>> (I'm not sure about >>, no <<= or >>=)

Other

no for await
no for ... in (unexpected string keys)

Special syntax

#!/usr/bin/env bun
#!/usr/bin/env node
#!/usr/bin/env deno

No-Conflict

Cannot be in conflict with https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Grammar_and_types or https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators

Nutty Things

void is among the Browser's best-kept secrets:

// ❌
var x = a + b(function () {
  // whatever
}())

// ✅
var x = a + b

void (function () {
  // whatever
}())

// ✅
var x = a + b;

(function () {
  // whatever
}());

// ❌ // b["apples,bananas,oranges"].forEach(...)
var x = a + b[
  "apples",
  "bananas",
  "oranges",
].forEach(function () {
  // ...
})

// ✅
var x = a + b

void [
  "apples",
  "bananas",
  "oranges",
].forEach(function () {
  // ...
})

// ✅
var x = a + b;

[
  "apples",
  "bananas",
  "oranges",
].forEach(function () {
  // ...
});

The text was updated successfully, but these errors were encountered:

coolaj86 pinned this issue Feb 8, 2023

coolaj86 changed the title ~~Language Spec~~ Language Draft Feb 10, 2023

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Language Draft #43

Language Draft #43

coolaj86 commented Feb 7, 2023 •

edited

Language Draft #43

Language Draft #43

Comments

coolaj86 commented Feb 7, 2023 • edited

Table of Contents

Questions

Guiding Principles

Ai JitScript by Example

Type System

Type Drafting

Concrete types

Functions

Special Functions

Variables

Expressions

Strings

Numbers

Macro System

Syntax

Keywords

Special Words

(Unused) Reserved Words

Non-Reserved Words

Syntax Characters

Other

Special syntax

No-Conflict

Nutty Things

coolaj86 commented Feb 7, 2023 •

edited