From mboxrd@z Thu Jan 1 00:00:00 1970 Received: (from majordomo@localhost) by pauillac.inria.fr (8.7.6/8.7.3) id KAA15713; Tue, 2 Jul 2002 10:49:58 +0200 (MET DST) Received: (from weis@localhost) by pauillac.inria.fr (8.7.6/8.7.3) id KAA15455 for caml-list@pauillac.inria.fr; Tue, 2 Jul 2002 10:49:58 +0200 (MET DST) Received: from nez-perce.inria.fr (nez-perce.inria.fr [192.93.2.78]) by pauillac.inria.fr (8.7.6/8.7.3) with ESMTP id GAA11366 for ; Tue, 2 Jul 2002 06:14:38 +0200 (MET DST) Received: from obento.cs.caltech.edu (obento.cs.caltech.edu [131.215.44.101]) by nez-perce.inria.fr (8.11.1/8.11.1) with ESMTP id g624Ebb01066 for ; Tue, 2 Jul 2002 06:14:37 +0200 (MET DST) Received: from orchestra.cs.caltech.edu (orchestra.cs.caltech.edu [131.215.44.20]) by obento.cs.caltech.edu (Postfix) with ESMTP id 8CBB8400E for ; Mon, 1 Jul 2002 21:14:35 -0700 (PDT) Received: (from mvanier@localhost) by orchestra.cs.caltech.edu (8.11.6/8.9.3) id g624EZf05386; Mon, 1 Jul 2002 21:14:35 -0700 Date: Mon, 1 Jul 2002 21:14:35 -0700 Message-Id: <200207020414.g624EZf05386@orchestra.cs.caltech.edu> X-Authentication-Warning: orchestra.cs.caltech.edu: mvanier set sender to mvanier@cs.caltech.edu using -f From: Michael Vanier To: caml-list@inria.fr Subject: [Caml-list] simple typing question Sender: owner-caml-list@pauillac.inria.fr Precedence: bulk I imagine this has been asked and answered before, so I apologize in advance. Compare these two functions: # let f x = List.map (fun y -> y) x ;; val f : 'a list -> 'a list = and # let f = List.map (fun y -> y) ;; val f : '_a list -> '_a list = Why does the second use the '_a type variable instead of 'a? I thought that special type variables only had to do with polymorphic references. The FAQ states that the latter expression can't be generalized, but I don't really understand why. Mike ------------------- To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/ Beginner's list: http://groups.yahoo.com/group/ocaml_beginners