Deleuze's book on Foucault can perhaps tell you something about Foucault's
functionalism. However, it is not a straightforward one. You need to tune
yourself for a while on Deleuze's own definitions in order to get the hunch
of a new functionalism. It is a complex conceptual journey. Anyway, it a
worthwhile to get on board.
Also, Kontopoulos; The logic of social structures can be also useful in
pointing out foucault's functionalism from an analytical approach.
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