lagenorhynque

> maybe "undefined" (show . (^ 2)) (Just 42)
"1764"

> maybe "undefined" (show . (^ 2)) Nothing
"undefined"

lagenorhynque

import java.util.*;

public class Bench {
    public static final int _keyRange = 100;
    public static final int _threadCount = 300;
    public static final int _repeat = 100000;

    //--------------------------------------------------------------------------------

    public static void main(String[] args) throws Exception {

lagenorhynque

user=> (def fact
  #_=>   ((fn [f]
  #_=>      ((fn [x] (x x))
  #_=>       (fn [y] (f (fn [& args] (apply (y y) args))))))
  #_=>    (fn [f]
  #_=>      (fn [n] (if (< n 2) 1 (* n (f (dec n))))))))
#'user/fact
user=> (for [n (range 10)] (fact n))
(1 1 2 6 24 120 720 5040 40320 362880)

lagenorhynque

user=> (let [z (+ x y)
  #_=>       x 1
  #_=>       y 2]
  #_=>   z)

CompilerException java.lang.RuntimeException: Unable to resolve symbol: x in this context, compiling:(/private/var/folders/pm/hsqkdvv91xn_wpq0fdpfsrz0tk36y9/T/form-init12874968895952326174.clj:1:9)
user=> (letfn [(z [] (+ (x) (y)))
  #_=>         (x [] 1)
  #_=>         (y [] 2)]
  #_=>   (z))

lagenorhynque

import Model

:set -XOverloadedStrings -XTypeFamilies -XFlexibleContexts

import Database.Persist.Sqlite

asSqlBackendReader :: ReaderT SqlBackend m a -> ReaderT SqlBackend m a
asSqlBackendReader = id

withDB :: (BaseBackend backend ~ SqlBackend,

lagenorhynque

// アカウント作成
personal.newAccount("sample")
personal.newAccount("sample2") // sample2がそのアカウントのパスフレーズになる

// 残高確認
web3.fromWei(eth.getBalance(eth.accounts[0]))

// マイニング: eth.accounts[0]に報酬が入る
miner.start()
miner.stop() // DAGを作ってるログが出たら、終わるまで待つ必要があるぽい

lagenorhynque

> :set -XRankNTypes
> :{
| twoList :: [a] -> [b] -> (forall c. [c] -> d) -> (d, d)
| twoList xs ys f = (f xs, f ys)
| :}
> twoList [1,2,3,4,5] ["hoge","fuga","piyo"] length
(5,3)

lagenorhynque

(ns polymorphism
  (:require [cats.context :as ctx]
            [cats.core :as m]
            [cats.protocols :as p]
            [cats.util :as util]))

(defn my-map [f coll]
  (lazy-seq
   (when-let [s (seq coll)]
     (cons (f (first s))

lagenorhynque

(ns cli
  (:require [clojure.spec.alpha :as s]))

(s/fdef sum
  :args (s/cat :coll (s/coll-of number?))
  :ret number?)

(defn sum [coll]
  (if (empty? coll)
    0

lagenorhynque

(ns channel-example
  (:require [clojure.core.async :as async]))

(defn -main []
  (let [ch1 (async/chan)
        ch2 (async/chan)
        ch3 (async/chan)]
    (async/go-loop []
      (let [i (async/<! ch1)]
        (async/>! ch2 (* i 2))