Chapter 1 - Introduction

Welcome to the Ena book! This book serves as a simple introduction to the Ena Programming Language.

Disclaimer

Ena is not complete yet. This means that Ena is not a mature language you would want to use for something serious. However, if you wanted to try something new, Ena is for you.

How is Ena different?

Unlike many other languages, Ena is a stack-based language. If you have worked with languages like Forth, you may find many Ena’s concepts similar to those in Forth.

Installing Ena

As of now, Ena does not provide any pre-built binaries. You will have to build it on your own.

The simplest way is to install Rust and then compile and install Ena:

$ cargo install enalang

You can also compile and install Ena from source:

$ git clone https://github.com/kislball/enalang
$ cd enalang
$ cargo install --path ./enalang

Hello, world!

The following code snippet describes a program which prints out a “Hello, world!” message.

# Comments are written using a hash sign

# Each Ena program is composed of blocks. Blocks are similar to functions, except that they do not accept
# any arguments.

# By default, Ena's VM uses `main` as the name for main block.

main {
  "Hello, world!" # Literals put values on stack. Blocks usually operate on stack.
  println # println prints the top value on stack, converts it into a string and prints it
}

Without comments:

main {
  "Hello, world!" println
}

Running

Ena uses a VM to run code. The VM cannot read Ena code directly; it reads an intermediate representation (IR) from Ena’s compiler.

First, compile your source code to IR:

$ ena compile ./hello_world.ena -o hello_world.enair

Next, compile the standard library (you only need to do this once):

$ ena compile "std/*.ena" -o std.enair

Link your program with the standard library:

$ ena link hello_world.enair std.enair -o executable.enair

Finally, run your program:

$ ena run ./executable.enair

You should now see a “Hello, world!” message.

For convenience, you can create a shell script to automate this process. The repository includes a run_example.sh script:

#!/bin/sh
# Usage: ./run_example.sh <filename_without_extension>

ena compile "std/*.ena" -o ./std.enair
ena compile ./examples/$1.ena -o ./main.enair
ena link ./main.enair ./std.enair -o output.enair
ena run ./output.enair
rm output.enair main.enair std.enair

What’s next?

In the next chapter, we will look into more details about coding in Ena.

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