ryohji

private val semaphore = AtomicBoolean(false)

private suspend fun Service.checkAndRefreshAccessToken() {
  val aSecond = 1000L
  var mills = 1L
  // wait (binary-) semaphore to ensure only one coroutine
  // executing this function's try ... catch body.
  while (!semaphore.compareAndSet(false, true)) {
    delay(millis)
    mills = minOf(aSecond, millis * 2)

ryohji

問題 2.6

対を手続きで表現することがそれほどの驚きでなければ，手続きを操作出来る言語では，0 と， 1 を足す演算を

(define zero (lambda (f) (lambda (x) x)))

(define (add-1 n)
 (lambda (f) (lambda (x) (f ((n f) x)))))

と実装することで，（少なくとも非負の整数だけを問題とする限りは）数を使わないで済せることが出来ることを考えよう．この表現は発明者 Alonzo Church（λ算法を発明した論理学者）に従い， Church 数 （Church numerals）として知られている．

ryohji

問題 2.4

これは対のもう一つの手続き表現である．この表現について任意のオブジェクト x と y に対し， (car (cons x y)) が x を生じることを証明せよ．

(define (cons x y)
 (lambda (m) (m x y)))

(define (car z)
 (z (lambda (p q) p)))

ryohji

diff --git a/app/src/main/java/com/example/android/codelabs/paging/data/GithubRepository.kt b/app/src/main/java/com/example/android/codelabs/paging/data/GithubRepository.kt
index b1b9b6c..c23688f 100644
--- a/app/src/main/java/com/example/android/codelabs/paging/data/GithubRepository.kt
+++ b/app/src/main/java/com/example/android/codelabs/paging/data/GithubRepository.kt
@@ -17,9 +17,8 @@
 package com.example.android.codelabs.paging.data
 
 import android.util.Log
-import androidx.lifecycle.MutableLiveData
+import androidx.paging.LivePagedListBuilder

ryohji

diff --git a/build.gradle b/build.gradle
index 29bd433..6a89632 100644
--- a/build.gradle
+++ b/build.gradle
@@ -26,6 +26,9 @@ kotlin {
         }
         macosTest {
         }
+        commonMain.dependencies {
+            implementation('org.jetbrains.kotlinx:kotlinx-coroutines-core-native:1.2.2')

ryohji

#include <cstdio>

int main() {
  auto z = [](auto f) {
    auto g = [&f](auto x) {
      return f([&x](auto y) { return x(x)(y); });
    };
    return g(g);
  };
  auto f = [](auto f) {

ryohji

const Z = f => (x => f(y => x(x)(y)))(x => f(y => x(x)(y)));
const fact = Z(f => x => x != 0 ? x * f(x-1) : 1);
fact(5); // => 120

ryohji

object Executor {
    val uiExecutor = Handler(Looper.getMainLooper()).toExecutor()
    val ioExecutor = LooperThread().also { it.start() }.getHandler().toExecutor()

    private fun Handler.toExecutor(): Executor = Executor {
        while (!post(it)) {
            Thread.sleep(0)
        }
    }

ryohji

package app

fun main() {
    val rules: List<Rule> = listOf(
        object : Rule {
            override val name = "read"
            override fun applicable(shared: Shared, thread: Thread) = thread.ir == Location.P0
            override fun convert(shared: Shared, thread: Thread) = shared to Local(Location.P1, shared.x)
        },
        object : Rule {

ryohji

val mutex = java.util.concurrent.locks.ReentrantLock()

const val FULL = 2
var que = 0

fun prod() {
    while (true) {
        // P0: lock
 mutex.lock()