Python as a first language Yoav Ram June 2018

Python is interpreted & dynamic Interpreter is great for novice programmers Dynamic type system allows fast prototyping

Python is high-level Design emphasizes code readability “looks like pseudocode”

Python design principles • Aims for simplicity and generality • Semantic whitespaces (newlines, indentation) • English keywords (and, or, not, in, is, as) • Operator overloading (”hello “ + “world”) There should be one—and preferably only one— obvious way to do it Wikipedia

Example: Hello World! Java public class HelloWorld { public static void main(String[] args) { System.out.println(“Hello World!”); } } Python print(“Hello World!”) Complex: classes, accessibility, arrays, functions, static, return type (void!), namespaces, standard output… and compilation. Simple. Try in online interpreter : tiny.cc/PyHelloWorl

Example: simple program def f2c(f=None): if f is None: f = input(“Enter F degrees: “) f = float(f) return (f – 32) * 5 / 9 def c2f(c=None): if c is None: c = input(”Enter C degrees: “) c = float(c) return 9 / 5 * c + 32 tiny.cc/PyF2C

Python is pluralist Cross-platform Multiple programming paradigms

Programming paradigms • Object-oriented programming (C++, Java, C#) • Imperative programming (C) • Functional programming (Haskell) • Event driven & async programming (JavaScript) – Co-routines (async) or callbacks (tornado) Wikipedia

OOP class Rectangle(Shape): def __init__(self, lower_left, upper_right): self.ll = lower_left self.ur = upper_right def area(self): width = self.ur.x – self.ll.x height = self.ur.y – self.ll.y return width * height def __contains__(self, point): return ( self.ll.x < point.x < self.ur.x and self.ll.y < point.y < self.ur.y )

Almost everything is an object • strings, lists, dictionaries, tuples, functions, classes, types • Strong polymorphism • Duck typing

Functional programming generators n = len(numbers) mean = sum(numbers) / n devs = (x – mean for x in numbers) squared_devs = (x*x for x in numbers) var = sum(squared_devs) / n std = var**0.5 def make_power(a): def power(x): return x**a return power square = make_power(2) square(4) # => 16 closure

Python is “batteries included” Large standard libraries Easy to install many 3rd party libraries Domain specific distributions

Large standard library • Files: zip, gzip, json, csv, tempfile, linecache, xml, wave • db: sqlite3, dbm • Network: socket, ssl, async • Web: urllib, http.server, email, ftplib, cgi, html, uu • Crypto: hashlib, hmac, secrets • Software: logging, unittest, mock, doctest, curses, sched, queue, getpass, gettext, tk,pdb, profiler • Concurrency: threading, multiprocessing, async, futures, subprocess • collections, functools, itertools… Python docs

Many new libraries released every month During 2015, > 1,500 new packages released every month to PyPI. See more stats at PyGarden/stats.

Python is free Gratis: Free as in Beer Libre: Free as in Speech GitHub | Mailing lists

Python is open Open-source software Community-based development Managed by non-profit Python Software Foundation

History of Python • Developed in 1989-91 by Guido van Rossum in the Netherlands • Python 2.0 released Oct 2000 • Many major new features: – cycle-detecting garbage collector – support for Unicode – shift to transparent and community-backed development • Python 3.0 released Dec 2008 – major backwards-incompatible release – many of major features backported to Python 2.6 and 2.7 • Python 3.5 released Sep 2015 • Python 3.7 beta available, final expected June 2018

Python is cool Jupyter notebooks, online interpreters, code on your phone, Raspberry Pi

Python is fast enough Easy to wrap more C Easy to parallelize Numerical packages implemented in C Cython: transcoder to C Numba: JIT compiler Benchmark Game | NumFocus Benchmarks

Python for data science & scientific computing With libraries like NumPy, SciPy, Matplotlib, IPython/Jupyter, Scikit-image, Scikit-learn, and more Replacing MATLAB Pushed by Google, Microsoft, others

Python is popular and has a great community

Easy to find help on the Internet • Python is 6th most popular tag on StackOverflow stackoverflow.com/tags, May 2018

Active community • 3rd most active repositories on GitHub after Java (incl. Android) and JavaScript (incl. node.js) • As of May 2018 • See breakdown at githut

Demand for Python programmers is high

Coding Dojo

Python is widely-used In academia In industry In education As Wikipedia examples…

Python is used at Google, Rackspace, Microsoft, Intel, Walt Disney, MailChimp, twilio, Bank of America, Facebook, Instagram, HP, Linkedin, Elastic, Mozilla, YouTube, ILM, Thawte, CERN, Yahoo!, NASA, Trac, Civilization IV, reddit, LucasFilms, D-Link, Phillips, AstraZeneca, Applied Materials, KLA-Tencor, Nova, Lam Research, Marvell https://us.pycon.org/2016/sponsors/ https://www.python.org/about/quotes/ https://en.wikipedia.org/wiki/Python_%28programming_language%29#Use https://en.wikipedia.org/wiki/List_of_Python_software https://www.python.org/about/success/

First language in US CS departments 1. Carnegie-Mellon: Python, C 2. MIT: Python 3. Stanford: Python, Java, JavaScript 4. Berkeley: Python 5. U Illinois UC: Python, Java, MATLAB, C 6. Cornell: Python, MATLAB 7. U Wash: Python, Java 8. Princeton: Java • Olin: Python Phillip Gou @ CACM

Phillip Gou @ CACM, 2014

First language in Israeli departments TAU: Python HUJI: Python Technion: C BGU: Java BIU: C Haifa: C Open U: Java 2017-2018

But why Python? Guido was reading some Monty Python's Flying Circus sketches and thought Python would be a cool name Python 2 FAQ

Encyclopædia Britannica Online Thanks for listening 32 yoav@yoavram.com @yoavram www.yoavram.com