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sumPairs :: [Integer] -> [Integer]
sumPairs (x:y:s) = (x + y) : sumPairs (y:s)
sumPairs _       = []

pascal :: Integer -> [Integer]
pascal 0 = [1]
pascal n = sumPairs $ [0] ++ (pascal $ n - 1) ++ [0]

sierpinski :: Integer -> String
sierpinski n = concat $ map (ascii . odd) $ pascal n

swr1bm86

import Control.Applicative ((<$>))

center :: String -> Int -> String
center s n = spaces ++ s ++ spaces
  where spaces = replicate ((n - length s) `div` 2) ' '

-- http://www.haskell.org/haskellwiki/Blow_your_mind, Ctrl-F "pascal"
pascal :: [[Int]]
pascal = iterate (\row -> zipWith (+) ([0] ++ row) (row ++ [0])) [1]

swr1bm86

(ns my.app
  (:require
   [aleph.http               :refer :all]
   [compojure.core           :refer [defroutes GET]]
   [compojure.handler        :as handler]
   [lamina.core              :refer :all]
   [com.netflix.hystrix.core :as hystrix]
   [clj-http.client          :as client]))

(defn get-pants []

swr1bm86

PROGRAM := llvm-brainfuck
OBJECTS := main.o
 
CXX := clang++
CXXFLAGS := $(shell llvm-config --cppflags) -Wall -Werror -pedantic
LDFLAGS := $(shell llvm-config --ldflags --libs core)
 
all: $(PROGRAM) $(SHIM)
 
$(PROGRAM): $(OBJECTS)

swr1bm86

• defprotocol: defines an interface
• deftype: create a bare-bones object which implements a protocol
• defrecord: creates an immutable persistent map which implements a protocol

Typically you'll use defrecord (or even a basic map);
unless you need some specific Java inter-op,
where by you'll want to use deftype instead.

Note: defprotocol allows you to add new abstractions in a clean way Rather than (like OOP) having polymorphism on the class itself,

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import Control.Monad.Reader

hello :: Reader String String
hello = do
    name <- ask
    return ("hello, " ++ name ++ "!")

bye :: Reader String String
bye = do
    name <- ask

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

/*
 * Lexical analyzer for Scheme-like minilanguage:
 * (define (foo x) (bar (baz x)))
 */
public class Lexer {
    public static enum Type {
        // This Scheme-like language has three token types:

swr1bm86

Y组合子是Lambda演算的一部分，也是函数式编程的理论基础。

它是一种方法/技巧，在没有赋值语句的前提下定义递归的匿名函数。
即仅仅通过Lambda表达式这个最基本的“原子”实现循环/迭代。
颇有道生一、一生二、二生三、三生万物的感觉。

虽然Y组合子在理论上很优美，但在实际开发中并不会真的用到。

想要了解Y组合子是什么，请参见维基百科：http://en.wikipedia.org/wiki/Fixed-point_combinator#Y_combinator
或者知乎上的回答：http://www.zhihu.com/question/20115649

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// Compositional evaluator as visitor

import java.math.BigInteger;

// Syntax

interface Exp {
    <X> X accept(Visitor<X> v);
}

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(defn fizzbuzz [n]
  (let [all-nums (range 0 n)
        folder (fn [fb-str p-num fb-coll]
                 (mapcat (fn [x] (cons fb-str (rest x)))
                         (partition-all p-num fb-coll)))
        fizz (folder "fizz" 3 all-nums)
        buzz (folder "buzz" 5 fizz)
        fizzbuzz (folder "fizzbuzz" 15 buzz)]
    fizzbuzz))