0005386: allow expression-level module open in field-assignment syntax - MantisBT

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ID

Project

Category

View Status

Date Submitted

Last Update

0005386

OCaml

OCaml general

public

2011-10-26 02:11

2011-12-20 09:07

Reporter

sweeks

Assigned To

Priority

normal

Severity

feature

Reproducibility

always

Status

resolved

Resolution

won't fix

Platform

OS

OS Version

Product Version

3.12.1

Target Version

Fixed in Version

Summary

0005386: allow expression-level module open in field-assignment syntax

Description

Given the following module declaration:
  module M = struct
    type t = { foo : int }
    let t = { foo = 13 }
  end

The following expression is accepted:

  let _ = M.(t.foo)

but the following is syntactically invalid:

  let () = M.(t.foo) <- 13;

It would be nice if it were accepted.

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Notes
(0006185) garrigue (manager) 2011-10-26 03:56	What is wrong with M.(t.foo <- 13) ? Are you concerned by putting the whole expression into scope? I really think we need a warning for local open hiding local identifiers... IIRC, Jun already has some code to do that, it would be a good idea to include it.

(0006186) sweeks (reporter) 2011-10-26 04:14	Yes, I prefer to restrict the scope of the open as much as possible.

(0006395) xleroy (administrator) 2011-12-20 09:07	OCaml has no notion of l-value expressions: "a.lbl <- b" is an AST node carrying "a" and "b" as subexpressions and "lbl" as node annotation. For this reason, a local open that would scope over "a" and "lbl" but not "b" simply doesn't fit the model and would need a special AST node + a special typing rule. It's not worth it, and I move to close this PR.

Issue History
Date Modified	Username	Field	Change
2011-10-26 02:11	sweeks	New Issue
2011-10-26 03:56	garrigue	Note Added: 0006185
2011-10-26 04:14	sweeks	Note Added: 0006186
2011-12-20 09:07	xleroy	Note Added: 0006395
2011-12-20 09:07	xleroy	Severity	minor => feature
2011-12-20 09:07	xleroy	Status	new => resolved
2011-12-20 09:07	xleroy	Resolution	open => won't fix

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