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Comment by ioddly | Hacker News Reader

That's cool! I actually tried something like this myself, but ended up with a less conventional syntax.

I'm not really familiar with Forth, but my impression from writing a little bit of postfix code was that some pattern matching would make e.g. writing a large conditional much easier.

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Forth is trivial to learn but takes serious effort to master, like Lisp and C. I'm a humble beginner myself when it comes to Forth. A match operator is a possibility, but too much of that will ruin all that's good about Forth. I already added word scoped variables, and I already feel like I'm balancing near the point of negative return.

That's something I'm working on, actually. I think matching the top stack item(s) fits well into a postfix stack-oriented language. For example:

  TYPE: Tree
    | Branch(Tree,Tree)
    | Leaf
    ;

  :: depth Tree -> Int ;
  : Branch($,$) depth {depth} dip depth + ;
  : Leaf depth 1 ;

$ is extract, so the pattern Branch($,$) pops the top of the stack and pushes the 2 members. Types and type constructors have to start with a capital letter, but I like the

  : Pattern word definition ;

syntax a lot.

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