gmichokostas

Hofstadter on Lisp

In the mid-80s, while reading through my roommate's collection of Scientific American back issues, I encountered this introduction to Lisp written by Douglas Hofstadter. I found it very charming at the time, and provide it here (somewhat illegally) for the edification of a new generation of Lispers.

In a testament to the timelessness of Lisp, you can still run all the examples below in emacs if you install these aliases:

(defalias 'plus #'+)
(defalias 'quotient #'/)
(defalias 'times #'*)
(defalias 'difference #'-)

gmichokostas

require 'pg'
PGDB = PG.connect(host: '/tmp', dbname: 'mydb')
PGDB.type_map_for_results = PG::BasicTypeMapForResults.new(PGDB)

class Hash
  def symbolize_keys
    inject({}) { |m, kv| v = kv[1];
      m[kv[0].to_sym] = v.is_a?(Hash) ? v.symbolize_keys : v; m }
  end
end

gmichokostas

#include <iostream>

using namespace std;

auto upto(int& beg, int& end) -> decltype(std::function<int()>()) {
    return [&]() {
        if (beg <= end) {
            return beg++;
        }
        return 0;

gmichokostas

package stack

import "fmt"

// Stack is a LIFO data structure
type Stack struct {
	len int
	top *node
}

gmichokostas

module GuessTheNumber where

import System.Random

startGame :: IO ()
startGame = do
  let tries = 5
  num <- randomRIO (0, 9) :: IO Int
  makeGuess num tries