Why Python?

This may be your first experience with programming, so I want to give you a sense of why we’re using Python, some of its advantages, and when you might want to use another language.

tl;dr: It’s a very readable language, is powerful enough for almost anything you want to do with it, and lots of people use it.

Dynamic vs Static (Types)

In statically typed languages such as Java, you have to declare the data type of every variable (such as numbers vs text). This makes compilers happy and can prevent bugs, but tends to involve a lot of boilerplate. When you’re frustrated with Python, remember, the language is managing all the data types for you, so cut it a break.

Compare the Java and Python versions of a simple program that prints “Hello, World!”:

Java

public class HelloWorld {

    public static void main(String[] args) {
        System.out.println("Hello, World");
    }

}

Python

print("Hello, World!")

Phew, that was easy!

Interpreted vs Compiled

Every programming language is an interface for controlling your computer. It uses the RAM, CPU, and Hard Drive to perform calculations. How is it that the magical code you type can do this? Well, it’s either a compiler or an interpreter.

A compiler takes computer code and processes it into binary instructions for a CPU. Very literally, ones and zeros. Compiled programs are very fast, but they only work for a limited set of computer architectures (see Note below), since different CPUs speak different dialects of binary. One of the most frustrating parts of working with a compiled languages is getting a program to compile without errors. It can be hard to find bugs because you can’t run the program to see what it does until you’ve run it. These kind of programs have major benefits, though, in that they’re very fast and very unlikely to crash. There are even some languages that are guaranteed not to crash once they’ve compiled. This is great for ubernerds and many of you may go on to code with compiled languages. But, luckily, we get to start with Python instead.

Compiled languages you may have heard of include C, C++, Java, FORTRAN, and Haskell.

An interpreter is a program that knows how to read a certain type of code and can translate that code into instructions for a certain CPU type on the fly. It has a general set of instructions and uses those to convert computer code into instructions for the CPU. So an interpreter only needs to be made once for a given CPU type- then the CPU can run all the programs in that interpreted language. Python falls in this category. Your Python code will run on any system that has an Python interpreter installed on it.

Interpreted Langauges you may have heard of include Python, Ruby, Javascript, R, and Perl.

Python programs will run even if they have bugs in them. They’ll run up until the point where the bug causes them to crash. This is a very useful feature, since it gives you important clues as to when and why the bug is happening. When you get frustrated with Python, remember that at least you don’t have to make your program compile before finding out what the bug is!

Note: There is great variability in the ways that languages are designed and executed. For instance, Java is a compiled language that uses a Virtual Machine to try to get around this limitation. A virtual machine (VM) is kind of like an interpreter, in that it takes instructions and translates them for the CPU, and you need one for each CPU type. You still have to compile Java programs, though once you do they (should) run on any Java VM. This is one of the reasons it became more popular than C as a teaching language. But Python is now overtaking Java because intepreters are so much more convenient for programmers than compilers are.

Whitespace-based syntax

Python uses whitespace (spaces, tabs, newlines, and other things that humans don’t see) to delineate the start and stop of its major pieces. Many other languages use a verbose syntax, which involves a lot of special characters.

The more explicit syntax is great for compilers and interpreters- it helps unambiguously tell them what to do. But it’s not so great for humans, since special characters have been shown to impede the comprehension of code’s meaning, especially for beginners.

Whitespace-based syntax tends to be very readable, since humans are good at seeing things spatially. For instance, in this Python program, it’s easy to grok, without knowing anything else, that lines 2 through 4 are ‘inside’ line 1, and that line 3 is ‘inside’ line 2.

1
2
3
4 def a_function():
    for i in range(10):
        print("something")
    print("something else")

Python used to be even easier to read: the print() function used to not require parentheses. But as of Python 3, it does, which makes the language more syntactically correct but harder for beginners. This is a rare misstep from the people who write the language. Trinket continues to support both forms of print, but we’ll be using the Python 3 version. Apologies for the loss in readability.