Abstract : We introduce another item in the already large list of techniques for attribute evaluation. Our algorithm consists in computing attributes by reductions to normal forms using a transducer operating on tree encodings of a cyclic representation of zippers. A zipper is a data structure introduced by Gérard Huet for representing a subtree together with its context, i.e. it is a tree with a focus that points to some node inside it. We mention some potential applications of this representation of attribute grammars as zipper transformers.