Mercurial > urweb
view src/prim.sml @ 213:0343557355fc
Explifying type classes
author | Adam Chlipala <adamc@hcoop.net> |
---|---|
date | Sat, 16 Aug 2008 14:45:23 -0400 |
parents | c0ea24dcb86f |
children | ed4af33681d8 |
line wrap: on
line source
(* Copyright (c) 2008, Adam Chlipala * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are met: * * - Redistributions of source code must retain the above copyright notice, * this list of conditions and the following disclaimer. * - Redistributions in binary form must reproduce the above copyright notice, * this list of conditions and the following disclaimer in the documentation * and/or other materials provided with the distribution. * - The names of contributors may not be used to endorse or promote products * derived from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. *) structure Prim :> PRIM = struct datatype t = Int of Int64.int | Float of Real64.real | String of string open Print.PD open Print fun p_t t = case t of Int n => string (Int64.toString n) | Float n => string (Real64.toString n) | String s => box [string "\"", string (String.toString s), string "\""] fun equal x = case x of (Int n1, Int n2) => n1 = n2 | (Float n1, Float n2) => Real64.== (n1, n2) | (String s1, String s2) => s1 = s2 | _ => false end