_________ ________ ____ __. .____ _____ _______ ________
\_ ___ \ \_____ \ | |/ _| | | / _ \ \ \ / _____/
/ \ \/ / | \| < | | / /_\ \ / | \/ \ ___
\ \____/ | \ | \ | |___/ | \/ | \ \_\ \
\______ /\_______ /____|__ \ |_______ \____|__ /\____|__ /\______ /
\/ \/ \/ \/ \/ \/ \/
Each interpreter is built to interpret a specific programming language. That's how you "implement" a programming language.
Without a compiler or interpreter, a programming language is nothing more than an idea or specification.
We will parse and evaluate our own language called cokLang.
- C-like syntax
- variable bindings
- integers and booleans
- arithmetic expressions
- built-in functions
- first-class and higher-order functions
- closures
- a string data structure
- an array data structure
- a hash data structure
let age = 1;
let name = "Monkey";
let result = 10 * (20 / 2);
Besides integers, booleans and strings, the cok interpreter we’re going to build will also support arrays and hashes. Here’s what binding an array of integers to a name looks like:
let myArray = [1, 2, 3, 4, 5];And here is a hash, where values are associated with keys:
let thorsten = {"name": "Thorsten", "age": 28};Accessing the elements in arrays and hashes is done with index expressions:
myArray[0] // => 1
thorsten["name"] // => "Thorsten"The let statements can also be used to bind functions to names. Here’s a small function that adds two numbers:
let add = fn(a, b) { return a + b; };But cok not only supports return statements. Implicit return values are also possible, which means we can leave out the return if we want to:
let add = fn(a, b) { a + b; };And calling a function is as easy as you’d expect:
add(1, 2);A more complex function, such as a fibonacci function that returns the Nth Fibonacci number, might look like this:
let fibonacci = fn(x) {
if (x == 0) {
0
} else {
if (x == 1) {
1
} else {
fibonacci(x - 1) + fibonacci(x - 2);
}
}make testREPL Examples:
