codeforkjeff

(defun my-replace (regex rep str &optional start)
  (save-match-data
    (let ((found-pos (string-match regex str (or start 0))))
      (if found-pos
          (let* ((match (substring str found-pos (match-end 0)))
                 (replacement (if (stringp rep)
                                  rep
                                (or (funcall rep match) ""))))
            (my-replace regex
                        rep

codeforkjeff

(defun my-replace (regex rep str &optional start)
  "Replace matches of regex in str with the result of applying
rep function to the match.

This exists because of a quirk in replace-regexp-in-string:
because it calls the REP function in a while loop that uses
string-match and replace-match, the REP function can't use
string-match without messing up the match state in the loop.

If rep returns nil, an empty string is used as the

codeforkjeff

(defun mask-ssn (num)
  (concat "XXX-XX-" (nth 2 (split-string num "-"))))

(replace-regexp-in-string "[0-9]\\{3\\}-[0-9]\\{2\\}-[0-9]\\{4\\}"
                          'mask-ssn
                          "Here's a number: 999-22-1111. Here's another: 222-11-9999.")

;; evaluates to "Here's a number: 999-22XXX-XX-11111111. Here's another: 222-11XXX-XX-99999999."

codeforkjeff

(defun mask-ssn (num)
  (save-match-data
    (concat "XXX-XX-" (nth 2 (split-string num "-")))))

(replace-regexp-in-string "[0-9]\\{3\\}-[0-9]\\{2\\}-[0-9]\\{4\\}"
                          'mask-ssn
                          "Here's a number: 999-22-1111. Here's another: 222-11-9999.")

;; evaluates to "Here's a number: XXX-XX-1111. Here's another: XXX-XX-9999."
;; Hooray!

codeforkjeff

(defun mask-ssn (num)
  (concat "XXX-XX-" (substring num 7)))

(replace-regexp-in-string "[0-9]\\{3\\}-[0-9]\\{2\\}-[0-9]\\{4\\}"
                          'mask-ssn
                          "Here's a number: 999-22-1111. Here's another: 222-11-9999.")

;; evaluates to "Here's a number: XXX-XX-1111. Here's another: XXX-XX-9999." 

codeforkjeff

# Compare the performance of python lists and sets when doing
# intersections.
#
# No real surprises here. Sets are faster than lists, and generating
# sets on-the-fly from lists is slightly slower than using sets to
# begin with.

import timeit
import random

codeforkjeff

;; Discovered via http://www.adampetersen.se/articles/fizzbuzz.htm
;; “Write a program that prints the numbers from 1 to 100. But for
;; multiples of three print “Fizz” instead of the number and for the
;; multiples of five print “Buzz”. For numbers which are multiples of
;; both three and five print “FizzBuzz”.”

(defun is-mult-p (n multiple)
  (= (rem n multiple) 0))

(defun fizzbuzz (&optional n)

codeforkjeff

;; Exercise 2.5 from SICP, in Common Lisp

(defun x-cons (a b)
  (labels ((x-power (x n &optional acc)
             (let ((acc (or acc x)))
               (if (= n 1)
                   acc
                   (x-power x (- n 1) (* acc x))))))
    (* (x-power 2 a) (x-power 3 b))))

codeforkjeff

#!/bin/sh
#
# Shell script that configures gnome-terminal to use solarized theme
# colors. Written for Ubuntu 11.10, untested on anything else.
#
# Solarized theme: http://ethanschoonover.com/solarized
# 
# Adapted from these sources:
# https://gist.github.com/1280177
# http://xorcode.com/guides/solarized-vim-eclipse-ubuntu/