How Rust Makes Advanced Type Systems Accessible to the Masses

By: Sunjay Varma

twitter.com/sunjay03

github.com/sunjay

Talk Outline

Dynamically-typed and Interpreted Languages
Type systems
Rust

Link to slides:

https://goo.gl/tSoLUS

These pictures are from 8-9 years ago!

Python

Great for learning and teaching
Online resources, tutorials, books
English-like syntax with "and", "or", and "not" which is readable for people with little or no programming background
Big ecosystem of libraries and many production users

import random
min = 1
max = 6

roll_again = "yes"

while roll_again == "yes":
    print "Rolling the dices..."
    print "The values are...."
    print random.randint(min, max)
    print random.randint(min, max)

    roll_again = raw_input("Again? ")

if (roll_again.startswith("never") and
    roll_again.endswith("ever")):

    print "I didn't want to play anyway."

elif not (roll_again.startswith("no") or
    roll_again.startswith("No")):

    print "That wasn't an option!"

Python

Interpreted

print "Favourite Animal Test"

prompt = "What is your favourite animal?"
fav = raw_input(prompt)

response = "That is a "
if fav == "dog":
    response += "great"

elif fav == "cat":
    response += "cool"

elif fav == "dragon":
    response += "unreal"

else:
    response += "awesome"

response += " choice!"
print response

 32 + "abc"

Dynamically Typed

This isn't valid

The Python interpreter evaluates programs line by line

# This will produce some text
ans = raw_input("Pick some letters: ")
# This will produce an integer
ans2 = int(raw_input("Pick some numbers: "))

# You can't add text to an integer, but
# Python will still run the above code
# before failing on this next line
print ans + ans2

# Dynamically typed also means that
# you can do something like this:
stuff = "abc"
stuff = 22

# stuff can be anything you want and
# the Python interpreter will only
# check it when you use it

Types

Types and type systems are a way to provide more information about your code to a program that can check your code automatically.

Program with Types

Type Checker

User

Feedback

Program

Types

You don't need types!

A human can check pretty much everything that a type checker could check for you
The question is: Why should we?
It is easy for computers to check a lot of these details for us
We just have to give them enough information to do that
Why spend your time doing something you can automate away?

Dynamically Typed

Python
Ruby
JavaScript
Racket/Lisp
Lua
PHP
and many more!

Statically Typed

C, C++, C#
Java
Rust
Haskell
Scala
Swift
and many more!

Types are checked while the program is running

Types are checked before the program can run

Rust

Rust is a statically typed, compiled language
In development since 2006, stable 1.0 version released in 2015
Most loved programming language in the StackOverflow developer survey two years in a row in 2016 and 2017
Fantastic community full of kind, compassionate and very knowledgeable people
Lots of great learning resources, thorough documentation, and people who are happy to answer your questions

Rust

Review: Types and type systems are a way to provide more information that can be checked beforehand
Rust checks for trivial errors like passing the wrong types to a function or using incompatible types with an operator
Programs that type check are guaranteed to be memory safe and not have any data races
You can write code that will not type check unless it is correct

Rust

The speed of C and C++, memory safety of Java, and the expressiveness of Haskell
Clean and relatively simple syntax that lets you focus on what you want to do and not need to write a lot of extra code to do it
From the FAQ: "We do not employ any particularly cutting-edge technologies. Old, established techniques are better."

Friends of Rust
https://www.rust-lang.org/en-US/friends.html

Takeaways

Rust makes advanced type systems accessible to everyone by having a great community, a fantastic set of features, and excellent learning resources
Type systems are good, important parts of programming languages that will reduce the amount of problems in your code
We should be using advanced type systems so that we can give the computers checking our code as much information as possible