Baby Steps

Clearly, every language requires a 'Hello, World!' program.

There are mainly three ways of executing citron code:

  • with the main executable ctr
  • with the scratchpad (neat thing, tbh) (see Scratchpad\)
  • with the (JIT) interpreter
  • compiling it with ctrc and executing that [this only generates a simple program that links into the Citron runtime, it is not static]

Using the Interpreter Prompt

Presumably, you have a terminal window open from back when you compiled citron from source, so switch to it,

and start the interpreter by executing citron and pressing <return>

Once you have started the interpreter, it will greet you with a nice-looking ascii art,

and the main prompt (default ⠕ )

Type Pen writeln: 'Hello, World!' followed by the return key.

You shall see the magical words Hello, World! printed to the screen. (and a [_:Object] which signifies the object Pen; in general, Objects without the method toString are shown in this format: [<name in current context>:Type])

Here's an example of what you might expect to see:

$ citron
Terminal: 24x83 - 0x0
  _____ _ _
 / ____(_) |
| |     _| |_ _ __ ___  _ __
| |    | | __| '__/ _ \| '_ \  Project Citron
| |____| | |_| | | (_) | | | |
 \_____|_|\__|_|  \___/|_| |_|

0.0.8.8-boehm-gc [GCC/G++ 8.2.0]
⠕ Pen writeln: 'Hello, World!'
Hello, World!
[_:Object]

How do I quit this interpreter?

Type :q and press return.

Or just press Ctrl + D.

or if you really like punching in expressions, evaluate Eval end

Choosing an editor

Currently, Atom, TextMate and Sublime 3 syntax files are generated and maintained.
However, minimal Smalltalk syntax highlighting will do in a pinch

Using a source file

Back to coding.

Open a new file [I have used main.ctr for most of the files] (generic extension is .ctr) and type this in:

Pen writeln: 'Hello, World!'.

Then simply run ctr with the sole argument being the path to the file.

$ ctr main.ctr
Hello, World!