Coming from TypeScript and JavaScript
What maps directly from TypeScript and JavaScript, the five habits that will trip you up, and the type tricks that have no counterpart.
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?. and ?? behave the same, and "tcp" | "udp" reads the same. The difference is the type checker: a TypeScript
type is a shape a value happens to fit, and a JavaScript value is whatever arrives. A TorbScript type is declared by
name, always checked, and has no way around the check.
At a glance#
| TypeScript / JavaScript | TorbScript | Note |
|---|---|---|
let x = 1; / const x = 1; | var x = 1 / const x = 1 | const also freezes everything inside the value |
undefined, null | Value? (Option<Value>) | one kind of missing value, and it is a type |
try { } catch (e) { } | Result<Value, Failure> and ? | a failure is in the signature |
interface Shape { area(): number } | trait Shape { fn area(): Float } | a type must say with Shape |
class Square implements Shape | type Square with Shape { } | no classes, no inheritance |
"tcp" | "udp" | "tcp" | "udp" | the same |
`${a} ${b}` | "{a} {b}" | every string interpolates |
arr.map(x => x * 2) | arr.map({ _ * 2 }) | lazy: nothing runs until a last step asks |
{ ...obj, x: 1 } | obj.copy(x: 1) | every type has copy |
switch with default | match | a forgotten case is a compile error |
function f(a: number, b = 1) | fn f(a: Int, b: Int = 1): Int | every parameter has a type |
value as Type | nothing | no casts: a conversion that can fail returns a Result |
value! | nothing | no non-null assertion |
enum Color { Red, Green } | type Color { case Red ... } | a case is its own value |
npm, package.json | torb, project.trb | one manifest, no bundler |
What changes in your code#
type Circle {
radius: Float
fn area(): Float {
3.0 * radius * radius
}
}
print Circle(2.0).area()
// prints 12.0There are no getters: a field is data, and a computed value is a method you call, area().
What TorbScript does not have#
No any, and no type that is "anything with these fields": a type is exactly what it declares. No union of unrelated
types, only of literals of one type. No Partial<T>, Pick<T, K> or index signatures, and no declare for untyped
code.
Habits to unlearn#
asto quiet the checker. Nothing gets past it; a conversion that can fail returns aResultor anOption.value!. Handle theNonecase, or give a fallback with??.- Patching a built-in through its prototype.
extendadds a trait, visible only where it is imported. while (true)orfor (;;). Writeloop { ... };while trueis an error that names it.- Overload signatures. A name means one function; a default value covers most overloads.
Related#
- Coming from TypeScript - the long version, with the reason for each difference.
- A tour of TorbScript - the rest of the language in fifteen minutes.
- Option -
SomeandNone, the one kind of missing value. - Syntax cheat sheet - every form of the language on one page.