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Dear all,
I have a problem when I use the memo-function to
implement a dynamic programming algorithm to traverse a graph.
I use the memo-function in the code
below:
dynamicPropagationUpAlg cname graph =
let
mh n = memo h n h n = let annotsuccs = (nub (concat (map (memo h) (succs n)))) in -- When the annotation set of the -- current node is empty, then we have to -- perform a if (length (myannots n) == 0) && ((length annotsuccs) > 1)then {- if length (succs n) > 1 then error ("<<Annotation failure>> Interface has to be annotated. "++(show n)) else -} case (trace ("Analyzing in component "++cname++"..\n"++"Before renaming successors annotations\n"++"Check for cycles in: \n"++"Comp: "++(getCompname n)++" Intf: "++(getIntfname n)++" Inst: "++(getFunname n)) (hasCycleInAnnots annotsuccs)) of Nothing -> map (replaceFunname (getCompname n)(getFunname n)) annotsuccs jMessage@(Just a) -> error (fromJust jMessage) else let mergeannots = mergeAnnotSets (annotsuccs++(myannots n)) (myannots n) in case (trace ("Analyzing in component "++cname++"..\n"++"After merging successors annotations\n"++"Check for cycles in: \n"++"Comp: "++(getCompname n)++" Intf: "++(getIntfname n)++" Inst: "++(getFunname n)) (hasCycleInAnnots mergeannots)) of Nothing -> mergeannots jMessage@(Just a) -> error (fromJust jMessage) g n@(InterfaceNode (annots, bo ,tp) names) = (InterfaceNode ((memo h n), bo, tp) names) succs n = (getSuccsOfNode n graph) myannots (InterfaceNode (annots,b,tp) names) = annots nodes = listNodes graph getFunname (InterfaceNode (annots, bo ,tp) (c,t,i)) = i getCompname (InterfaceNode (annots, bo ,tp) (c,t,i)) = c getIntfname (InterfaceNode (annots, bo ,tp) (c,t,i)) = t in map (g) nodes The idea is that the every node in the graph is
visited only once, moreover that the function "h" is computed only once for
every node.
My implementation is not working properly. I don't
know the cause for my problem, so can anyone hint me one the right use of the
memo-function?
Thanks in advance..
Kind regards,
Tom
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