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authorGravatar Adam Chlipala <adamc@hcoop.net>2008-08-08 17:55:51 -0400
committerGravatar Adam Chlipala <adamc@hcoop.net>2008-08-08 17:55:51 -0400
commitb9b67597324deb6e6dfc8ef33c60c110abc2af7b (patch)
tree2ff5f7417692c2590916a6eeb55aa38bbb47516f /src/order.sml
parente2a9136ed7123cb8e5cac4a20cbce5467643ecd6 (diff)
Specialization of single-parameter datatypes
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+(* 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.
+ *)
+
+(* Utility code for implementing comparisons *)
+
+structure Order :> ORDER = struct
+
+fun join (o1, o2) =
+ case o1 of
+ EQUAL => o2 ()
+ | v => v
+
+fun joinL f (os1, os2) =
+ case (os1, os2) of
+ (nil, nil) => EQUAL
+ | (nil, _) => LESS
+ | (h1 :: t1, h2 :: t2) =>
+ join (f (h1, h2), fn () => joinL f (t1, t2))
+ | (_ :: _, nil) => GREATER
+
+end