0005358: first class modules don't allow "with type" declarations for types in sub-modules

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0005358

OCaml

OCaml general

public

2011-09-20 12:12

2012-09-25 20:07

Reporter

yminsky

Assigned To

frisch

Priority

normal

Severity

minor

Reproducibility

always

Status

closed

Resolution

fixed

Platform

OS Version

Product Version

3.12.1

Target Version

Fixed in Version

3.13.0+dev

Summary

0005358: first class modules don't allow "with type" declarations for types in sub-modules

Description

For some reason, 1st-class modules have more restrictive "with" syntax, which turns out to be a practical problem.

The main constraint is that with constraints do not seem to be able to refer to sub-modules. Consider the following code snippet:

> module type Foo = sig type t end
> module type Bar = sig module Foo : Foo end
>
> (* compiles *)
> let g (type a) (m : (module Foo with type t = a)) = ()
>
> (* fails to compile with a syntax error *)
> let f (type a) (m : (module Bar with type Foo.t = a)) = ()

It would be nice to lift this restriction. (Also, allowing "with module" declarations would be good.)

Additional Information

There's a thread discussing this initiated by this message:

https://sympa-roc.inria.fr/wws/arc/caml-list/2011-09/msg00158.html [^]

with a useful explanation by Alain Frisch here:

https://sympa-roc.inria.fr/wws/arc/caml-list/2011-09/msg00162.html [^]

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Notes
(0006287) frisch (developer) 2011-12-14 11:28	Wish granted (commit 11311). Camlp4 compiles but cannot parses the new feature. TODO: - adapt the manual - adapt Camlp4

(0006334) dim (developer) 2011-12-16 19:05	I updated Camlp4 (commit 11320).

(0006335) frisch (developer) 2011-12-16 19:38	Thanks Jérémie. I've updated the manual, so feel free to mark the issue as resolved if you're confident in the camlp4 update.

Issue History
Date Modified	Username	Field	Change
2011-09-20 12:12	yminsky	New Issue
2011-12-14 11:04	frisch	Assigned To	=> frisch
2011-12-14 11:04	frisch	Status	new => assigned
2011-12-14 11:28	frisch	Note Added: 0006287
2011-12-16 19:05	dim	Note Added: 0006334
2011-12-16 19:38	frisch	Note Added: 0006335
2011-12-17 10:12	dim	Status	assigned => resolved
2011-12-17 10:12	dim	Resolution	open => fixed
2011-12-17 10:12	dim	Fixed in Version	=> 3.13.0+dev
2012-09-25 20:07	xleroy	Status	resolved => closed