GrantLang

A (Terrible) Beam Language

Good articles https://andrealeopardi.com/posts/tokenizing-and-parsing-in-elixir-using-leex-and-yecc/

Understanding Parser Basics https://lark-parser.readthedocs.io/en/latest/parsers/

The Elixir Parser https://github.com/elixir-lang/elixir/blob/master/lib/elixir/src/elixir_parser.yrl

The Elixir Tokenizer https://github.com/elixir-lang/elixir/blob/master/lib/elixir/src/elixir_tokenizer.erl

Building an interperter https://ruslanspivak.com/lsbasi-part1/

Notes

Vocab:

A lexer will tokenize a sequence of bytes.

The syntax of a leex rule is this:

Regular expression : Erlang code.

TODO

• Strings
  • Double quote single line
  • Heredoc
  • escaped newlines
  • escaped quotes (the current processer is striping the out with replace)
• Functions
  • Call "stdlib functions"
  • Define functions
  • Functions as values?
  • Anon funcs?
  • import / export
• Have && and || short circuit
• Pemdas
• String/Array concat (<<)
• REPL
• Basex -> GrantLang full name change
• Split out GrantLang vm into its own module
• Mix compiler to load .grant files into a project
• Concurrency
  • @foo @bar BEAM node global vars
  • async && await
  • atomic { expressions... } block syntax

DONE

• Comments
  • nested comments
• Comparators / Boolean Logic
  • > < <= >=
  • == !=
  • && ||
• Math operators
  • + - / * **
• If statements
  • else
• Maps
  • Literals
  • bracket indexing
  • Dot access
• Arrays
  • literals
  • numeric indexing ($arrays[10])
• For loops
  • for ($val <- $array) { $val + 1 } // $array
  • for ($val <- $map) { $val + 1 } // $map
  • for ($index, $val <- $array) { $val + 1 } // $array
  • for ($key, $val <- $map) { $val + 1 } // $map
• While Loops
  • Break Statement
• $foo++ $foo-- operators
• $foo ||= $bar operator
• ! negation operator
• Negative Numbers

Sample

// I'm a comment!
/* I'm a block comment
see me span multiple lines */

// assignment
$foo <- [1,2,3];
$bar <- true || false;

// literals
$integer <- 1;
$float <- 1.0;
$negative_int <- -1;
$negative_float <- -1.0;
$string <- "foo";
$array <- [1,2,3];
$map <- &{
  "foo" => "bar",
  "baz" => 1.0
  1 => 2,
  [1,2,3] => (4 + 5)
};

//increment + decrement
$i++;
$i--;

// indexing
$array[1];
$array[$index];
$map[$key];
$map.key; // only for string keys

// comparison / boolean logic
$result <- (1 < 2) && (3 >= 5) || ( 5 != 6);

// if statement 
if (true || false) { "foo" } else { "bar" };

// while loop
$i <- 1; 

while ($i < 4) { $i++ };

// for loop
for ($i <= $foo) {
  if ($i > 2) { $std_lib.echo($i) } else { $i };
};

// for loops as `map`
$result <- for ($i <- [1,2,3]) { $i + 1 } // $result == [2,3,4]

// assignment from an if statement
$result <- if ($RAND > 0.5) { 4 } else { 5 };

General Notes

• Comments were the first time I had to deal with significant whitespace, "//" comments are ended by a new line, and it took me a minute to figure that one out
• String escaping is really really hard...