tokland

import React from "react";

export interface OptControlledValue<T> {
    value?: T;
    set?: (value: T) => void;
    initial: T;
}

export function useMaybeControlledValue<T>(options: OptControlledValue<T>): [T, (val: T) => void] {
    const optionsSet = options.set;

tokland

#!/bin/bash

# Start a UI app and move its window to a specific Xfce workspace.
#
# Example: Move app xoscope to workspace number 2 (starts at 1).
#
#   $ run-in-workspace 2 xoscope

run_in_workspace() {
    local workspace=$1

tokland

#!/bin/bash
set -e -u -o pipefail

# Open a new pull request in github from the current branch
open_pr() {
    local base_branch=${1:-"development"}
    local merge_organisation_opt=${2:-}
    local browser="xdg-open"
    local repo current_branch merge_organisation merge_branch url

tokland

type AllKeysOfUnion<U> = U extends any ? keyof U : never;

type NonCommonKeysOfUnion<U> = Exclude<AllKeysOfUnion<U>, keyof U>;

type PartialBy<T, K extends keyof T> = Omit<T, K> & Partial<Pick<T, K>>;

type UnionWithKeys<U, K extends keyof any> = U extends any
    ? { [Key in K]: Key extends keyof U ? U[Key] : never }
    : never;

tokland

const canvas = document.getElementById("tutorial");
const context = canvas.getContext("2d");

function drawBackground() {
    context.beginPath();
    context.fillStyle = "rgb(200, 200, 200)";
    context.rect(0, 0, 640, 480);
    context.fill();
    context.closePath();
}

tokland

/* Naturals using Peano numbers. See https://ostro.ws/2019/12/09/taking-types-too-far/ */

type Zero = { prev: never };
type Nat = { prev: Nat };
type Succ<N extends Nat> = { prev: N };
type Prev<N extends Nat> = N["prev"];

type Nats = {
    0: Zero;
    1: Succ<Zero>;

tokland

type Length<T extends any[]> = T["length"];
type Head<T extends any[]> = T[0];
type Tail<T extends any[]> = ((...xs: T) => any) extends (x: any, ...t: infer T) => any ? T : never;

type Last<T extends any[]> = {
    0: never;
    1: T[0];
    ">1": Last<Tail<T>>;
}[Length<T> extends 0 ? 0 : Length<T> extends 1 ? 1 : ">1"];

tokland

function renderJoin(nodes: ReactNode[], separator: ReactNode): ReactNode {
    return nodes.flatMap((node, idx) =>
        idx < nodes.length - 1 ? [node, separator] : [node]
    ).map((node, idx) => <React.Fragment key={idx}>{node}</React.Fragment>);
}
          
// Usage
          
const myComponent: React.FC = props => { 
  return <div>{renderJoin([<p>item1</p>, <p>item2</p>], <br />)}</div>;

tokland

export type Matcher<KindField extends string, Kind extends string, Obj, Result> = {
    [K in Kind]: (obj: Extract<Obj, { [F in KindField]: K }>) => Result;
};

export function match<KindField extends string>(field: KindField) {
    return function<
        Obj extends { [K in KindField]: Kind },
        Result,
        Kind extends string = Obj[KindField]
    >(obj: Obj, matcher: Matcher<KindField, Kind, Obj, Result>): Result {

tokland

const letters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";

function idOf(idx: number): string {
    const quotient = Math.floor(idx / letters.length);
    const remainder = idx % letters.length;
    return (quotient > 0 ? idOf(quotient - 1) : "") + letters[remainder];
}

function cell(colIdx: number, rowIdx: number): string {
    return idOf(colIdx) + (rowIdx + 1).toString();