Tagged dungeon crawlers

It's high time for more Another Syntactic Monstrosity examples, but first let's take a look at its development.


I spent the last few days on redesigning the parsing strategy, ATM the interpreter reads the raw input, lexes it using static, immutable grammar specs and then parses the token stream into an AST, all this hardcoded in D.This proves to be fast, but it's nearly non-tweakable. That's not what I intended ASM to be and it makes some neat features, such as overriding Tuple evaluator, impossible.

The new parsing strategy reminds of CommonLisp reader and reader-macros:

  • The raw input is passed to the lexer (written in D) that uses dynamic syntax table - a set of regular expressions describing the syntax (defined in ASM) to tokenize the input into a token stream.
  • Next, the token stream is passed to the parser (written in ASM with default implementation in D), that uses ASM functions, correlated to the syntax table, to dispatch the token stream and translate it to basic, lispy S-expressions (see LR parser for details on how it's done).This will allow ASM to act like any other language, given there's the syntax table available, making it perfect for DSL programming.

For example:

(lambda (x y) (pow (+ x y) 2))

...might be written as:

[x y => (x + y)^2]

...and ASM will happily accept it. Awesome!

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