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annotate demo/list.ur @ 1974:a10368c65e7f

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Add day-of-week/month <-> int conversion functions.
author Patrick Hurst <phurst@mit.edu>
date Sat, 07 Dec 2013 21:31:51 -0500
parents 669ac5e9a69e
children
rev   line source
adamc@397 1 datatype list t = Nil | Cons of t * list t
adamc@397 2
adamc@823 3 fun length [t] (ls : list t) =
adamc@501 4 let
adamc@501 5 fun length' (ls : list t) (acc : int) =
adamc@501 6 case ls of
adamc@501 7 Nil => acc
adamc@501 8 | Cons (_, ls') => length' ls' (acc + 1)
adamc@501 9 in
adamc@501 10 length' ls 0
adamc@501 11 end
adamc@397 12
adamc@823 13 fun rev [t] (ls : list t) =
adamc@501 14 let
adamc@501 15 fun rev' (ls : list t) (acc : list t) =
adamc@501 16 case ls of
adamc@501 17 Nil => acc
adamc@501 18 | Cons (x, ls') => rev' ls' (Cons (x, acc))
adamc@501 19 in
adamc@501 20 rev' ls Nil
adamc@501 21 end