Ur/Web: demo/treeFun.ur annotate

Basic handling of recursive functions in Iflow

author	Adam Chlipala <adamc@hcoop.net>
date	Sat, 01 May 2010 09:51:46 -0400
parents	311ca1ae715d
children

rev	line source
adamc@469	1 functor Make(M : sig
adamc@469	2 type key
adamc@469	3 con id :: Name
adamc@469	4 con parent :: Name
adamc@469	5 con cols :: {Type}
adamc@469	6 constraint [id] ~ [parent]
adamc@469	7 constraint [id, parent] ~ cols
adamc@469	8
adamc@723	9 val key_inj : sql_injectable_prim key
adamc@469	10
adamc@706	11 table tab : ([id = key, parent = option key] ++ cols)
adamc@469	12 end) = struct
adamc@469	13
adamc@469	14 open M
adamc@469	15
adamc@469	16 fun tree (f : $([id = key, parent = option key] ++ cols) -> xbody)
adamc@469	17 (root : option M.key) =
adamc@469	18 let
adamc@469	19 fun recurse (root : option key) =
adamc@471	20 queryX' (SELECT * FROM tab WHERE {eqNullable' (SQL tab.{parent}) root})
adamc@469	21 (fn r =>
adamc@469	22 children <- recurse (Some r.Tab.id);
adamc@469	23 return <xml>
adamc@469	24 <li> {f r.Tab}</li>
adamc@469	25
adamc@469	26 <ul>
adamc@469	27 {children}
adamc@469	28 </ul>
adamc@469	29 </xml>)
adamc@469	30 in
adamc@469	31 recurse root
adamc@469	32 end
adamc@469	33
adamc@469	34 end

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