Return-Path: Delivery-Date: Received: from ted.cs.uidaho.edu by swan.cl.cam.ac.uk with SMTP (PP-6.2); Tue, 20 Oct 1992 11:22:44 +0100 Received: by ted.cs.uidaho.edu (16.6/1.34) id AA13701; Tue, 20 Oct 92 03:10:34 -0700 Sender: info-hol-request@edu.uidaho.cs.ted Errors-To: info-hol-request@edu.uidaho.cs.ted Precedence: bulk Received: from ganymede.inmos.co.uk by ted.cs.uidaho.edu (16.6/1.34) id AA13646; Tue, 20 Oct 92 03:10:02 -0700 Received: from frogland.inmos.co.uk by ganymede.inmos.co.uk; Tue, 20 Oct 92 11:08:53 BST From: David Shepherd Message-Id: <2984.9210201008@frogland.inmos.co.uk> Subject: Re: Error in variant -- Can anyone explain... To: kimdam@dk.tfl (Kim Dam Petersen) Date: Tue, 20 Oct 92 11:08:38 BST Cc: info-hol@edu.uidaho.cs.ted (info-hol mailing list) In-Reply-To: ; from "Kim Dam Petersen" at Oct 19, 92 5:05 pm X-Mailer: ELM [version 2.3 PL11] Kim Dam Petersen has said: > > According to the Reference Manual > > variant : term list -> term -> term > > never fails. Nevertheless the simple application: > > variant ["T"] (mk_var(`x`,":num"));; > > yields the error message: > > evaluation failed VARIANT from the code its clear that variant expects the term list to be a list of variables. for a more general version you could use let gen_variant tml tm = variant (itlist append (map frees tml) []) tm;; which primes tm so it doesn't clash with any free variables in any term in tml. -------------------------------------------------------------------------- david shepherd: des@inmos.co.uk or des@inmos.com tel: 0454-616616 x 625 inmos ltd, 1000 aztec west, almondsbury, bristol, bs12 4sq 1992: celebrate the quincentenary of columbus getting lost