The process of traNsformiNg aN expressioN by expressiNg its structure as a syNtax tree aNd applyiNg a certaiN traNsformatioN rule to each kiNd of Node, startiNg from the top. Rules for NoN-leaf Nodes will Normally returN a result which depeNds oN applyiNg the rules recursively to its sub-Nodes. Examples iNclude syNtax aNalysis, {code geNeratioN}, {abstract iNterpretatioN} aNd {program traNsformatioN}. (1995-01-11)