src/ZF/Sum.thy
author lcp
Thu May 04 02:01:49 1995 +0200 (1995-05-04 ago)
changeset 1108 22b256c8c9fb
parent 753 ec86863e87c8
child 1401 0c439768f45c
permissions -rw-r--r--
case is defined using pattern-matching
     1 (*  Title: 	ZF/sum.thy
     2     ID:         $Id$
     3     Author: 	Lawrence C Paulson, Cambridge University Computer Laboratory
     4     Copyright   1993  University of Cambridge
     5 
     6 Disjoint sums in Zermelo-Fraenkel Set Theory 
     7 "Part" primitive for simultaneous recursive type definitions
     8 *)
     9 
    10 Sum = Bool + "simpdata" +
    11 consts
    12     "+"    	:: "[i,i]=>i"      		(infixr 65)
    13     Inl,Inr     :: "i=>i"
    14     case        :: "[i=>i, i=>i, i]=>i"
    15     Part        :: "[i,i=>i] => i"
    16 
    17 defs
    18     sum_def     "A+B == {0}*A Un {1}*B"
    19     Inl_def     "Inl(a) == <0,a>"
    20     Inr_def     "Inr(b) == <1,b>"
    21     case_def    "case(c,d) == (%<y,z>. cond(y, d(z), c(z)))"
    22 
    23   (*operator for selecting out the various summands*)
    24     Part_def	"Part(A,h) == {x: A. EX z. x = h(z)}"
    25 end