Node Interpreter

A Node/Typescript interpreter for the monkey programming language, based on the excellent book "Writing An Interpreter In Go".

⚙️ Installation

To get started, clone the repository:

git clone https://github.com/bpetermann/node-interpreter.git
cd node-interpreter

Then, install dependencies and build the project:

npm run build:fresh // Installs dependencies and builds the project

🚀 Start

Finally, start the REPL (Read-Eval-Print Loop):

npm run start // Starts the REPL

📋 Usage Examples

>> let a = 2; // Declare a variable
>> let baz = ["foo", "bar"]; // Declare an array
>> baz[0]; // Acesss array
>> let person = {"name": "Alice"}; // Declare a hash map
>> person["name"]; // Access map

Here's a basic example illustrating the declaration and invocation of a function:

>> let a = 2; // Declare a variable
>> let multiply = fn(x, y) { x * y }; // Declare a function
>> multiply(50 / 2, a); // Call the function
50

Example of closures:

>> let newAdd = fn(x) {
  fn(y) { x + y };
};
>> let addTwo = newAdd(2);
>> addTwo(2);
4

Close the REPL:

eof;

Interpreter Workflow

1. Lexical Analysis (Lexer):

• The input code undergoes tokenization by the Lexer, breaking it into smaller units known as tokens (keywords, identifiers, operators).

2. Parsing:

• Tokens are organized into an abstract syntax tree (AST) by the Parser, following the grammar rules specific to the language.
• The AST represents the hierarchical structure of the code, arranging statements and expressions.

3. Evaluation:

• The interpreter traverses the AST, evaluating nodes and executing code based on the languages syntax rules.

This interpreter employs a process of lexical analysis, parsing, and evaluation to systematically analyze and execute code, creating an AST to interpret programs according to the specific syntax and rules of the language.

Syntax Overview

The syntax embodies a rich spectrum of functionalities, managing mathematical expressions, variable assignments, function definitions, calls, conditionals, and returns. It adeptly handles concepts like higher-order functions and closures.

Additionally, the interpreter accommodates diverse data types — integers, booleans, strings, arrays, and hashes.

It also features a set of built-in functions tailored to expedite string/array operations and console output logging.

🧪 Tests

The following command will run all jest test suites:

npm run test