@sthir/number

@sthir/number

Function and types to work with numbers. Currently only includes e and E to facilitate @sthir/predicate's & comparator usage, but will include more functions and types in future.

☝🏻 Note: It requires typescript version 4.8 and higher

e

An eDSL to write numeric-expressions that evaluate compile-time to produce more complete and narrow types.

import * as N from "@sthir/number"

let a: 0b01 = 0b01
let b: 0b10 = 0b10

let c: 0b11 = a | b
// doesn't compile: Type 'number' is not assignable to type '3'.

let d: 0b11 = N.e(`${a} | ${b}`)
// compiles

You can also use the macro version in @sthir/number/macro that uses babel-plugin-macro to transform N.e(\${a} | ${b}`)intoa | b` for zero runtime overhead.

Supported operators are &, |, <<. We can have more operators but currently only these have a compelling use-case for using bitflag predicates with @sthir/predicate. If you have compelling use-cases for other operators feel free to open an issue.

E

Type-level version of e

import * as N from "@sthir/number"

type A = 0b01
type B = 0b10
type C = A | B
// C is `0b01 | 0b10` because `|` is union not bitwise or

type D = N.E<`${A} | ${B}`>
// D is `0b11`