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comparison lib/ur/list.ur @ 839:b2413e4dd109

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List library additions; fix another substructure unification bug
author Adam Chlipala <adamc@hcoop.net>
date Sat, 06 Jun 2009 14:09:30 -0400
parents d07980bf1444
children e4a02e4fa35c
comparison
equal deleted inserted replaced
838:5154a047c6bc 839:b2413e4dd109
120 case f x st of 120 case f x st of
121 (y, st) => fold (y :: ls') st ls 121 (y, st) => fold (y :: ls') st ls
122 in 122 in
123 fold [] 123 fold []
124 end 124 end
125
126 fun assoc [a] [b] (_ : eq a) (x : a) =
127 let
128 fun assoc' ls =
129 case ls of
130 [] => None
131 | (y, z) :: ls =>
132 if x = y then
133 Some z
134 else
135 assoc' ls
136 in
137 assoc'
138 end
139
140 fun search [a] [b] f =
141 let
142 fun search' ls =
143 case ls of
144 [] => None
145 | x :: ls =>
146 case f x of
147 None => search' ls
148 | v => v
149 in
150 search'
151 end
152