List notation

[rolyp]

• do Broken syntax for nullary constructors #49 first?
• infix cons (::)
• Haskell-style list notation [a, b, c], with [x, ...xs] as notation for cons
• revisit continuation-passing idiom for trie-parsing? (requires trie zipper)
• extend notation to pattern-matching

[rolyp]

Most brain-dead list notation that doesn't require two distinct notations (e.g. :: and [x, y, ...] in Haskell).

[jamescheney]

In Prolog (and I think Erlang also) "cons" can be written [x|xs] and you can write [x,y,z|xs] for cons(x,cons(y,cons(z,xs))).

[rolyp]

Ok, that's useful to know - thanks! That's what I've just implemented, but with "..." instead of "|" (reminiscent of ES6 spread notation).

   fun mergesort xs →
      match xs as {
         [] → xs;
         [x] → xs;
         [x, y, ...xs'] →
            match split xs as 
               (ys, zs) → merge (mergesort ys) (mergesort zs)
      }

Implementing that for list patterns turned out to be quite tricky because the syntax of tries requires the pattern parser to be written in a continuation-passing style..gah.