A type with finite number of elements - OCaml

Question

I'm using CIL to process C programs using the pthread library. I have to process user-defined and non-pthread functions differently from pthread functions. Can I have a type definition which looks something like:

type PThreadFun = "pthread_create" | "pthread_join" | ...;;

so that I first pattern-match on the function name and then send it to either

processFunction (fn_name: string)

or

processPThreadFun (fn_name: PThreadFun)

Answer 1

You can have sum types in OCaml, they are called variants. But their values are not strings. You could declare

type pthreadfun_t = Pthread_create | Pthread_join (* etc *);

^{Then you'll need some code processing the CIL representation to find such pthreadfun_t values.}

BTW, you might be interested by MELT, which is a domain specific language to extend the GCC compiler. MELT works on the internal GCC representations, notably Gimple. It is not Ocaml or CIL based, but it is a GCC plugin giving you a powerful Lisp-like domain specific language with powerful pattern-matching, including ability to match Gimple-s, Tree-s, strings, etc...