Types for Delimited Continuations

• CM.hs: an implementation of Danvy-Filinski’s shift and reset as a delimited continuation indexed monad (based on Atkey’s “Parameterised Notions of Computation”).
• df.rkt: a redex model of Danvy-Filisnki’s shift and reset type system with answer type changing (broken I think).
• callcc.rkt: a redex model of “delimited callcc”, based on Racket’s behavior (this actually found a bug in Racket lol).