Comment author: administrator

Full_Name: Fermin Reig
Version: version 3.00+22 (2001-02-05)
OS: alpha linux
Submission from: giro.gla.ac.uk (130.209.6.41)

In this or-pattern

let f1 = function
Some n -> 0
| None | Some 1 -> 1

"Some 1" is an unused match case. The compiler does not report it.
For a similar or-pattern

let f2 = function
n -> 0
| 0 | 1 -> 1

"1" is correctly reported as an unused match case.

This is rather a plea for a new feature than a plain bug.

In f1, the second clause
| None | Some 1 -> 1
is not unsused since its pattern matches ``None''.

The clause is in some sense partially unused, since it can
be simplified into ``| None -> 1''

In your second example, the clause is a true unused ine : its
pattern never matches.

Flagging ``partially unused clausses'' is a good
idea.

--Luc Maranget

Comment author: administrator

Done in 3.05 (Luc Maranget).