ocaml.type support for parametric types

[ygrek]

Consider :

$ cat q.proto 
type l = [ int ] options "ocaml.type" = "int list, f, g"
$ extprotc q.proto
Fatal error: exception Failure("Cannot print \"int list\" this string contains more than one token")

Ideally I would like to be able to write

type list 'a = [ 'a ] options "ocaml.type" = "'a list, f, g"

but this might have some typing complications that I may not be aware of, while the former (specialized type without free variables) seems to be only hindered by printing bug..

[ygrek]

For some reason latest commit handles polymophic types but trips on string list (it generates abstract type instead o_O) but String.t list works. I am puzzled.

[mfp]

On Mon, Jan 11, 2016 at 08:37:56PM -0800, ygrek wrote:

For some reason latest commit handles polymophic types but trips on string list (it generates abstract type instead o_O) but String.t list works. I am puzzled.

String.t also works for me with OCaml 4.02.3, but I get a different error for string list:

$ cat q.proto 
type l = [ string ] options "ocaml.type" = "string list, f, g"

$ OCAMLRUNPARAM=b compiler/extprotc q.proto 
Parse error in OCaml type: Stream.Error("illegal begin of ctyp")
in
string list
Fatal error: exception Loc.Exc_located(_, _)
Raised at file "camlp4/Camlp4/Struct/Loc.ml", line 306, characters 16-35
Called from file "camlp4/Camlp4/Struct/Grammar/Entry.ml", line 59, characters 57-78
Called from file "gen_OCaml.ml", line 141, characters 4-49
Re-raised at file "gen_OCaml.ml", line 145, characters 10-11
Called from file "gen_OCaml.ml", line 171, characters 57-75
Called from file "gen_OCaml.ml", line 409, characters 14-60
Called from file "gencode.ml", line 322, characters 8-40
Called from file "extList.ml", line 154, characters 9-12
Called from file "extList.ml", line 162, characters 1-13
Called from file "gencode.ml", line 303, characters 15-18
Called from file "extprotc.ml", line 119, characters 21-80
Called from file "option.ml", line 25, characters 13-16

$ cat q2.proto 
type l = [ string ] options "ocaml.type" = "String.t list, f, g"

$ compiler/extprotc q2.proto
$ cat q2.ml 
module L =
  struct
    type l = String.t list;;
    let pp_l ppf x = Extprot.Pretty_print.pp_list Extprot.Pretty_print.pp_string ppf (g x);;

  end;;

Mauricio Fernández

[ygrek]

Looks like it cannot parse any "compound" type starting with lident :(

[mfp]

Worse, it chokes on lident itself :-/ (OCaml 4.02.3, camlp4 4.02+6)

[mfp]

And Camlp4OCamlParser.ml leaves no doubt it should be covered (as if there were any chance it weren't to begin with...):

          | i = a_LIDENT -> <:ctyp< $lid:i$ >>

[ygrek]

One more observation: it works for char char list int64 list but not for int or string. Also note that Camlp4.Precast.Gram parses all those fine.

[ygrek]

The real reason is the extension of grammar in compiler/parser.ml which modifies Camlp4.PreCast.Gram which conflicts with later usage in compiler/gen_OCaml.ml. Proper fix pushed.

[mfp]

Thank you! The dangers of uncontrolled global side-effects :-/