The stupidest, messiest, most horrible interpreter for the most useless language you've never seen.
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The Quetzal Profarting Language

This was a weekend project because what the heck. Actually, this was a weekend project because an incompetent Concurrent Programming professor made us do a syntactic analyser as a final project... but I decided to be really stupid and make an interpreter that actually works. Sorta.

I've never had a class on compilers, so I don't know anything about interpreters and all that fancy stuff, except for what I've learned by poking at other people's code (that, is almost nothing).

Strings are REALLY broken, and if you ever try to do anything useful with it, it will probably eat you alive.

Also, never, ever, ever read the source. Seriously, don't do it. It's the worst piece of shit you will never see, because you'll be a well–behaved person and you will not look at it, because I told you not to. Ok?

Okay, I am assuming you're back to reading this, after you went and read the source. Look at you, you subversive little shit. Don't flame me if you did—I did warn you.

Oh yeah, error messages are in spanish because I'm Mexican.


There are only three keywords. There are no comments. There are no operators.

  • let: Defines variables
  • proc: Defines procedures
  • return: Returns values from procedures

All instructions must end in a semicolon. There is no fancy "everything is an expression" concept here; the only expressions are calling procedures that return something and assigning that to variables.

Procedures are defined like this:

proc do_some_shit(param1 int, param2 string) int {
    return param1;

proc no_return_no_params() {

Variables are defined like this:

let a int = 5;
let b string = "foo";
let c int = do_some_shit(a, "bar");

You can pass literals or variables to procedures. <-- Yeah, it's that awesome.

You can't nest procedure calls, so everything is super verbose.

Type System

There's only two types: int and string. There's no variable re–assignment. Also, you can't return literals from functions because I'm a lazy fuck and didn't implement that.

There's no type inference; all variables must specify their types.

There is some type safety: You can't pass variables of mismatched types to procedures, and you can't assign results from procedures to variables of mismatched types.

All variables are scoped locally to their parent procedure.


Programs must have a main procedure, and all procedures and variables must be defined before they are used.


There's a few built–in procedures:

  • suma: Add
  • sub: Subtract
  • mult: Multiply
  • print: Print (duh)

All of these take two parameters except for print which takes one, and is the only type–flexible procedure (it takes either int or string). All of these return int except for print which returns nothing. I don't know what happens if you try to assign the value of print to a variable and then try to use it, so your computer might explode if you do that.


Compile it, and run it passing the resulting binary a path to a file as the first argument.


go build -o quetzal main.go
./quetzal file.quetzal


proc square(a int) int {
    let b int = mult(a, a);
    return b;

proc main() {
    let c int = square(5);
    print("This should return 25:\n");