kohyama

Clojure tips infrequently used

To get names of methods of a class

(map #(.getName %) (.getMethods java.io.File))
; -> ("equals" "toString" "hashCode" "compareTo" "compareTo" "getName" "length" "getParent" "isAbsolute" "getCanonicalPath" "setReadOnly" "list" "list" "delete" "getParentFile" "getPath" "getAbsolutePath" "getAbsoluteFile" "getCanonicalFile" "toURL" "toURI" "canRead" "canWrite" "exists" "isDirectory" "isFile" "isHidden" "lastModified" "createNewFile" "deleteOnExit" "listFiles" "listFiles" "listFiles" "mkdir" "mkdirs" "renameTo" "setLastModified" "setWritable" "setWritable" "setReadable" "setReadable" "setExecutable" "setExecutable" "canExecute" "listRoots" "getTotalSpace" "getFreeSpace" "getUsableSpace" "createTempFile" "createTempFile" "wait" "wait" "wait" "getClass" "notify" "notifyAll")

kohyama

(ns check-inline
  (:gen-class))

(defmacro sqr-m [n] `(* ~n ~n))

(definline sqr-i [n] `(* ~n ~n))

(defn sqr-fwi
  {:inline (fn [n] `(do (println "inline:") (* ~n ~n)))}
  [n] (do (println "function:") (* n n)))

kohyama

Project Euler Problem 10 解答とコメント

#clojure 入門者向け勉強会 #mitori_clj 第二週担当分

Project Euler Problem 10
2,000,000 未満の素数の総和を求めよ. とのことです.

結果を出すために手に入るリソースを有効活用するという考えのもとでは --この問題自体の解答を述べている

kohyama

(defn hanoi-ops [s t d n]
  (if (zero? n) '()
      (concat
        (hanoi s d t (dec n))
        (list [n s d])
        (hanoi t s d (dec n)))))

(hanoi-ops 'A 'B 'C 4)
; -> ([1 A B] [2 A C] [1 B C] [3 A B] [1 C A] [2 C B] [1 A B] [4 A C]
;     [1 B C] [2 B A] [1 C A] [3 B C] [1 A B] [2 A C] [1 B C])

kohyama

(define-module synhl
  (use text.tree)
  (export highlight))
(select-module synhl)

;(use slib)
;(require 'trace)

(define (mk-tokenizer :rest args)
  (letrec

kohyama

(require '[clojure.set :refer (difference)])

(defn sudoku-level0 [coll]
  (let [ics (vec (map #(if % #{%} (set (range 1 10))) coll))
        cnb (fn [cs i]
              (set
                (keep #(if (= 1 (count %)) (first %))
                  (concat
                    (map first (partition-all 1 9 (drop (mod i 9) cs)))
                    (take 9 (drop (* 9 (quot i 9)) cs))

kohyama

(defn fibs [a b]
  (cons a (lazy-seq (fibs b (+ a b)))))

(take 100 (fibs 1N 1N))
; -> (1N 1N 2N 3N 5N 8N 13N 21N 34N 55N 89N 144N 233N 377N 610N 987N
;     1597N 2584N 4181N 6765N 10946N 17711N 28657N 46368N 75025N
;     121393N 196418N 317811N 514229N 832040N 1346269N 2178309N
;     3524578N 5702887N 9227465N 14930352N 24157817N 39088169N
;     63245986N 102334155N 165580141N 267914296N 433494437N
;     701408733N 1134903170N 1836311903N 2971215073N 4807526976N

kohyama

(defn fizz-buzz [n]
  (map #(cond (zero? (mod % 15)) "FizzBuzz"
              (zero? (mod % 5)) "Buzz"
              (zero? (mod % 3)) "Fizz"
              :else %)
       (range 1 (inc n))))

(fizz-buzz 100)
; -> (1 2 "Fizz" 4 "Buzz" "Fizz" 7 8 "Fizz" "Buzz" 11 "Fizz" 13 14 "FizzBuzz"
;     16 17 "Fizz" 19 "Buzz" "Fizz" 22 23 "Fizz" "Buzz" 26 "Fizz" 28 29 "FizzBuzz"

kohyama

This gist has moved to https://gist.github.com/3937083 To be deleted near future

kohyama

# Usage:
#   Save this file as 'hello.s'.
#   $ as -o hello.o hello.s
#   $ ld -o hello   hello.o
#   $ ./hello
#
# How to call a system call
#   1) Set rax to the index of the system call.
#   2) Set rdi, rsi, rdx, ... to arguments in this order.
#   3) Call 'syscall'.