The following OCaml base types are supported:
| OCaml type | XDR type |
|---|---|
unit | void |
int | int |
int32 | int |
int64 | hyper |
float | double |
bool | bool |
char | enum 0..255 |
string | string<> |
Also supported are built-in compound types ([['a]] is the XDR equivalent of 'a):
| OCaml type | XDR type |
|---|---|
'a * 'b * ... | struct { [['a]] 0; [['b]] 1; ... } |
{ foo : 'a; ... } | struct { [['a]] foo; ... } |
Foo of 'a ... | union switch () { case 0: [['a]] 0; ... } |
`foo of 'a ... | union switch () { case 0: [['a]] 0; ... } |
'a array | [['a]]<> |
'a list | union switch () { case 0: void 0; case 1: [['a list]] 1 } |
'a option | [['a]] * |
'a ref | [['a]] |
Finally, new types may be defined in the usual way, possibly with type parameters. However, a parameterized type must be instantiated when used in a remote function declaration (see Functions). The XDR equivalent of an instance of a polymorphic type is just the (XDR equivalent of the) type with the actual types substituted in.
Type equations are permitted; you must also give the definition of the type so orpc can generate marshalling functions for it.
Mutable record fields and refs are permitted, although of course changing a field on one end of a network connection does not change it on the other.