fResult

// Usage:
import isEven from "is-not-odd";

isEven(3); // false
isEven(4); // true

// In index.ts of `is-not-odd` module
import isOdd from "is-odd";

type PredicateFn<T> = (...args: [T, ...any[]]) => boolean;

fResult

import { compose, isEmpty, map } from 'lodash/fp';
import { useQuery } from '@tanstack/react-query';

// USAGE
// This makes us read "mapStrapiResponse toStaticContent AFTER fetchSomeStaticPageContent"
const fetchAndMapContent: () => Promise<SomeStaticContentAttrs> = compose(
  mapStrapiResponse(toStaticContent),
  fetchSomeStaticPageContent,
);
const pageContent: SomeStaticContentAttrs = await fetchAndMapContent();

fResult

// MSS - Maximum Sum Segment problem
// MSS = maximum . map sum . concat . map inits . tails
// Playground - https://tsplay.dev/mpzE6w
function tail<T>(xs: T[]): T[] {
  return xs.slice(1)
}

function init<T>(xs: T[]): T[] {
  return xs.slice(0, -1)
}

fResult

export type UnaryFn<T, R> = (arg: T) => R;

export function compose<R>(fn: UnaryFn<any, R>): UnaryFn<any, R>;
export function compose<T1, R>(fn1: UnaryFn<T1, R>): UnaryFn<T1, R>;
export function compose<T1, T2, R>(
  fn2: UnaryFn<T2, R>,
  fn1: UnaryFn<T1, T2>
): UnaryFn<T1, R>;
export function compose<T1, T2, T3, R>(
  fn3: UnaryFn<T3, R>,

fResult

Higher-Order Functions 😡😡😡

See something from an actual Maths book.

Definition

A function is called a higher-order function if its arguments and values are allowed to be functions.
This is an important property that most good programming languages possess.
The composition and tupling operations are examples of functions that take other functions as arguments and return functions as results.

fResult

function zip(xs, ys) {
  if (xs.length < ys.length) {
    return xs.map((x, idx) => [x, ys[idx]])
  } else {
    return ys.map((y, idx) => [xs[idx], y])
  }
}

// FP Style

fResult

Functors and natural transformations (Continue)

แบบฝึกหัดจากรอบที่แล้ว

แบบฝึกหัดใหม่

เราจะมารู้เรื่อง Category $\Bbb{Rel}$ กัน แต่ก่อนจะเข้าใจเรื่อง Relation ได้ ต้องเท้าความเรื่อง Category of Set ก่อน กำหนดให้มี Category $\Bbb{Set}$ ที่มี Object เป็น $Set$(s) ต่างๆ มี Morphism เป็น function(s) มี Identity Morphism เป็น $1_x=x$ (หรือ $f\ x=x$)

fResult

import IconFacebook from '../components/icons/IconFacebook'
import IconTwitter from '../components/icons/IconTwitter'

function YourPage() {
  const [hoveredIcons, setHoveredIcons] = useState({
    fb: false,
    tw: false,
    ig: false,
    pt: false,
  })

fResult

function IconFacebook({ fill = "#FFF", width = 24, height = 24 }) {
    return (
        <svg xmlns="http://www.w3.org/2000/svg" width={width} height={height}>
            <path
                fill={fill}
                d="M22.675 0H1.325C.593 0 0 .593 0 1.325v21.351C0 23.407.593 24 1.325 24H12.82v-9.294H9.692v-3.622h3.128V8.413c0-3.1 1.893-4.788 4.659-4.788 1.325 0 2.463.099 2.795.143v3.24l-1.918.001c-1.504 0-1.795.715-1.795 1.763v2.313h3.587l-.467 3.622h-3.12V24h6.116c.73 0 1.323-.593 1.323-1.325V1.325C24 .593 23.407 0 22.675 0z"
            />
        </svg>
    )
}

fResult

{
  "Create TypeScript React Arrow Functional Component and  for `.tsx` file": {
    "prefix": "tsrafce",
    "body": [
      "import React, { FC } from 'react'",
      "",
      "type ${1:${TM_FILENAME_BASE}}Props = {",
      "  className?: string",
      "  ${2:prop1}: ${3:type1}",
      "}",