Jooyung Han jooyunghan

async 라이브러리로 JavaScript의 콜백헬을 조금이나마 피할 수 있는 모양이다.

뒤늦게 async를 살펴보았다. API들이 잘 이해가 안되었는데, 알고보니 비교적 단순한 원리로 만들어진 것들이었다. sync버전의 대응함수와 비교해보면, 함수 그자체와 iterator 함수들을 모두 async로 바꾼것에 불과하다.

each :: Array[A] -> (A->Unit) -> Unit
async.each :: Array[A] -> (A->(Unit->Unit)->Unit) ->(Unit->Unit)->Unit

map :: Array[A] -> (A->B) -> Array[B]

node-postgres라이브러리 위키에는 아래의 예제 코드가 나온다. Transaction으로 insertion을 두 번 하는 코드다.

var Client = require('pg').Client;

var client = new Client(/*your connection info goes here*/);
client.connect();

var rollback = function(client) {

	-- euler67
	-- input file: https://projecteuler.net/project/resources/p067_triangle.txt

	readInput = map (map read . words) . lines

	solve = foldr1 merge
	where merge xs ys = zipWith (+) xs $ zipWith max ys (tail ys)

	main = do
	content <- readFile "p067_triangle.txt"

	import com.googlecode.totallylazy.Sequence;
	import com.googlecode.totallylazy.Strings;
	import com.googlecode.totallylazy.numbers.Integers;
	import org.junit.Test;

	import java.util.ArrayList;
	import java.util.List;

	import static com.googlecode.totallylazy.Pair.functions.first;
	import static com.googlecode.totallylazy.Pair.pair;

	<!DOCTYPE html>
	<html>
	<head>
	<title>Functional Flappy</title>
	</head>
	<style type="text/css">
	#playground {
	width: 500px;
	height: 500px;
	border: 1px solid red;

	@Test
	public void no18_2() throws Exception {
	String input = "75\n" +
	"95 64\n" +
	"17 47 82\n" +
	"18 35 87 10\n" +
	"20 04 82 47 65\n" +
	"19 01 23 75 03 34\n" +
	"88 02 77 73 07 63 67\n" +
	"99 65 04 28 06 16 70 92\n" +

	package com.jooyunghan;

	import fj.P2;
	import fj.data.List;
	import fj.data.Stream;

	import static fj.P.p;
	import static fj.Show.*;
	import static fj.data.List.list;
	import static fj.data.Stream.iterate;

	import Graphics.Collage exposing (filled, rect, collage, toForm)
	import Graphics.Element exposing (image, beside, below, above, empty, Element, spacer, color)
	import Graphics.Input exposing (customButton, button)
	import Color exposing (red, yellow)
	import Signal exposing ((<~))
	import Markdown

	off_bulb = collage 30 30 [
	toForm (image 28 28 "data:image/jpeg;base64,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

	(ns fox-goose-bag-of-corn.puzzle)

	(def start-pos [[[:fox :goose :corn :you] [:boat] []]])

	(defn end? [state]
	(= state [#{} #{:boat} #{:you :goose :fox :corn}]))

	(defn next-moves' [[left boat right]]
	(cond (left :you)
	(into [[(disj left :you) (conj boat :you) right]] ;; move alone