Original bug ID: 1359
Reporter: administrator
Status: closed
Resolution: not a bug
Priority: normal
Severity: minor
Category: ~DO NOT USE (was: OCaml general)

Bug description

Full_Name: Stefan Kral
Version: 3.06
OS: SuSE Linux 7.0 (i386)
Submission from: a49.dialin.tuwien.ac.at (192.35.240.59)

Hi,

I have problems mixing sum-types and records.
Having read nowhere that this is illegal, I
assumed that the following should work...
(also, because references are similarly defined)

First try:

stefan@schlaubi:~/ml > ocaml
Objective Caml version 3.06

type tree =

| Empty 
| Node of complexnode      

and complexnode =
{
mutable pos : int;
s0 : tree;
s1 : tree;
};;
type tree = Empty | Node of complexnode
type complexnode = { mutable pos : int; s0 : tree; s1 : tree; }

{ pos = 1, s0 = Empty, s1 = Empty };;

Characters 11-13:
{ pos = 1, s0 = Empty, s1 = Empty };;
^^
Unbound value s0

At first, I thought that this might be related to the mutable field, pos.
So I tried the same with a record-type containing only immutable fields...

stefan@schlaubi:~/ml > ocaml
Objective Caml version 3.06

type tree =

| Empty 
| Node of complexnode      

and complexnode =
{
pos : int;
s0 : tree;
s1 : tree;
};;
type tree = Empty | Node of complexnode
type complexnode = { pos : int; s0 : tree; s1 : tree; }

{ pos = 1, s0 = Empty, s1 = Empty };;

Characters 11-13:
{ pos = 1, s0 = Empty, s1 = Empty };;
^^
Unbound value s0

Next, I thought that the mutually recursive definition might pose a problem.

stefan@schlaubi:~/ml > ocaml
Objective Caml version 3.06

type tree =

| Empty 
| Node of tree * tree;;

type tree = Empty | Node of tree * tree

type complexnode =

{ 
  mutable pos : int; 
  s0 : tree; 
  s1 : tree;
};;

type complexnode = { mutable pos : int; s0 : tree; s1 : tree; }

{ pos = 1, s0 = Empty, s1 = Empty };;

Characters 11-13:
{ pos = 1, s0 = Empty, s1 = Empty }
^^
Unbound value s0

I tried different names (as a substitute for s0), without success.
First, I thought that the identifier of the second field is always
the culprit.

But then I tried changing the order of fields in the definition
of the record-type...

    Objective Caml version 3.06

type tree =

| Empty 
| Node of tree * tree;;

type tree = Empty | Node of tree * tree

type complexnode =

{ 
  s0 : tree; 
  mutable pos : int; 
  s1 : tree;
};;

type complexnode = { s0 : tree; mutable pos : int; s1 : tree; }

{ s0 = Empty; pos = 1; s1 = Empty };;

• : complexnode = {s0 = Empty; pos = 1; s1 = Empty}

Alas, it seems so work ;-) I can't help but think that the
other definition(s) should have worked just as well...

Regards,
Stefan