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from django.conf import settings
from django.db import models

# A Batch represents one batch, and may be assigned to multiple
# users.
class Batch(models.Model):
    name = models.CharField(max_length=200)
    assigned_users = models.ManyToManyField(settings.AUTH_USER_MODEL, blank=True)

    def __str__(self):

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{-# LANGUAGE GADTs, RankNTypes, TypeFamilies, DataKinds, DeriveFunctor, TypeOperators  #-}

import Data.Type.Equality
import Data.List (intercalate)
import Data.Maybe (catMaybes)

data HasVars = Var | NoVar

data SHasVars a where
  SVar :: SHasVars Var

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Javascript Review

Table of contents

1. Objects
2. Functions
3. Closures
4. The call and apply methods
5. Prototypes and constructors

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import requests
import os

twilio_sid = os.environ['TWILIO_SID']
twilio_auth = os.environ['TWILIO_AUTH']
twilio_url = 'https://api.twilio.com/2010-04-01/Accounts/%(twilio_sid)s/SMS/Messages.json' % locals()

weather_url = 'http://api.openweathermap.org/data/2.5/weather'
weather_params = {'q': 'montreal'}
r = requests.get(weather_url, params=weather_params)

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from random import randint

def run(goal, runs):
  total = 0
  for x in xrange(runs):
    sequence = []
    for i in xrange(3):
      sequence.append(randint(0,1))
    while sequence[-3:] != goal:
      sequence.append(randint(0,1))

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var quote = String.fromCharCode(39);
var source = [
  'var quote = String.fromCharCode(39);',
  'var source = [',
  '  ',
  '];',
  'console.log(source[0]);',
  'console.log(source[1]);',
  'source.forEach(function(line) {',
  '  console.log(source[2] + quote + line + quote + ",");',

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Proposition: If $f : A \to \mathbb{R}$ is continuous at $c \in A$, $kf$ is continuous at $c$ for $k \in \mathbb{R}$ Proof: Let $\epsilon > 0$ be given. Since $f$ is continuous at $c$, $\exists \delta > 0$ such that if $|x - c| < \delta$ then $|f(x) - f(c)| < \epsilon / (|k| + 1)$. Thus if $|x - c| < \delta$:

$$ |kf(x) - kf(c)| = |k||f(x) - f(c)| \leq \frac{|k|\epsilon}{|k| + 1} = \frac{|k|}{|k|+1}\epsilon < \epsilon $$

If we want to show that the product of two continuous functions is continuous, we need the following lemma:

Lemma: If $f : A \to \mathbb{R}$ is continuous at $c \in A$, $f$ is bounded in a neighborhood of $c$. Proof: Let $\epsilon = 1$. As $f$ is continuous at $c$ we know there exists some $\delta &gt; 0$ such that if $|x - c| &lt; \delta$, then $|f(x) _ f(c)| &lt; \epsilon = 1$. By the triangle inequality, we can go on to say that $|f(x)| - |f(c)| \leq |f(x) - f(c)| &lt; 1$, therefore $|f(x)| &lt; 1 + |f(c)| = M$. Thus if $|x - c| &lt; \delta$, then $|f(x)| &lt; M$, i.e. it is bounded.

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data StockState = StockState { hi :: Int, lo :: Int, lowest :: Int }
  deriving Show

solve xs = (hi st) - (lo st)
  where
    st = solve' xs

solve' [] = StockState 0 0 0
solve' (x:xs) = foldl go (StockState 0 0 x) xs
  where

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var _ = require('underscore');

var freqVector = function(word, letters) {
  var freq = _.groupBy(word.split(''), function(l) {return l;});
  return _.map(letters, function(l) {
    return freq[l] ? freq[l].length : 0;
  }); 
};

var dot = function(v1, v2) {

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function counter(times, callback) {
  var ct = 0;
  return function() {
    ct++;
    if (ct === times)
      callback();
  };
};

// register a counter function