0005155: Toplevel doesn't accept the type info it writes itself. - MantisBT

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ID

Project

Category

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Date Submitted

Last Update

0005155

OCaml

OCaml general

public

2010-09-26 21:53

2012-09-19 14:13

Reporter

yziquel

Assigned To

garrigue

Priority

normal

Severity

minor

Reproducibility

always

Status

resolved

Resolution

suspended

Platform

OS

OS Version

Product Version

3.12.0

Target Version

4.01.0+dev

Fixed in Version

Summary

0005155: Toplevel doesn't accept the type info it writes itself.

Description

Here's a type declaration that is accepted. However the type information that is returned isn't accepted by the toplevel.

yziquel@seldon:~$ ocaml
Objective Caml version 3.12.0

# type 'a t = private ( < .. > as 'a);;
type 'a t = private < .. > constraint 'a = 'a t
# type 'a t = private < .. > constraint 'a = 'a t;;
Error: The type constraints are not consistent.
Type 'a is not compatible with type 'a t
#

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Notes
(0005668) garrigue (manager) 2010-10-02 11:31	I admit the situation is confusing. However, I have no easy fix at this point. Parsing of type expressions is so complicated that fixing this is bound to break something else... Two remarks: 1) I'm afraid this definition is not what you intended. It defines a private row type, whose parameter is constrained to be itself. This is not a private abbreviation, and actually this type ends up not being usable. 2) If you want a private abbreviation, the declaration should be type 'a t = 'a constraint 'a = < .. > This version gets printed correctly.

(0005670) yziquel (reporter) 2010-10-03 21:21	Thanks. I believe that type 'a t = 'a constraint 'a = < .. > is indeed what I want. Couldn't it be possible to make the toplevel print this type declaration instead of the following? type 'a t = < .. > constraint 'a t = 'a It seems to me that the main issue is the fact that 'a is implicit in < .. >. Wouldn't it be better to have a way to make it explicit? Like < .. as 'a >?

(0008112) doligez (manager) 2012-09-19 14:13	This type definition is not accepted anymore in 4.00.0, so the problem disappeared.

Issue History
Date Modified	Username	Field	Change
2010-09-26 21:53	yziquel	New Issue
2010-10-02 11:18	garrigue	Status	new => assigned
2010-10-02 11:18	garrigue	Assigned To	=> garrigue
2010-10-02 11:31	garrigue	Note Added: 0005668
2010-10-03 21:21	yziquel	Note Added: 0005670
2012-07-10 17:48	doligez	Target Version	=> 4.01.0+dev
2012-07-31 13:36	doligez	Target Version	4.01.0+dev => 4.00.1+dev
2012-09-19 14:11	doligez	Target Version	4.00.1+dev => 4.01.0+dev
2012-09-19 14:13	doligez	Note Added: 0008112
2012-09-19 14:13	doligez	Status	assigned => resolved
2012-09-19 14:13	doligez	Resolution	open => suspended

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