Font-lock fails for type expressions

[ghost]

Font-lock rules seems to be failing to apply to type expressions in many cases.

These cases fail for me:

(* type signatures never work *)
val x : int
val f : int -> int
(* inline function type signatures - parameters seem to break it *)
let f x : int = x + 1

Only non-function values declared with let and type definitions work.

[Chris00]

If you are talking about the types not being highlighted, that is a design decision. I try to highlight the types when they are introduced, not so much when they are used — although I do in some cases such as (x: t). Highlighting all the signatures after val was not completely reliable — it is hard to know when they finish with regexps — and, IMHO, not very useful — val and the function name are highlighted, what follows is necessarily a signature. For the case let f x : t =, I could highlight t since it is "lost" inside another expression and coloring it may help readability.

[ghost]

For consistency, the let case is important to have, and it does help readability. I also think highlighting val types would also be more consistent. But it's not as useful, so I won't push it.

Thanks for adding this, though.