Cross-stage persistence is an essential aspect of multi-stage programming that allows a value defined in one stage to be available in another. However, difficulty arises when implicit information held in types, type classes and implicit parameters needs to be persisted. Without a careful treatment of such implicit information—which are pervasive in Haskell—subtle yet avoidable bugs lurk beneath the surface.
This paper demonstrates that in multi-stage programming care must be taken when representing quoted terms so that important implicit information is not discarded. The approach is formalised with a type-system, and an implementation in GHC is presented that fixes problems of the previous incarnation.
Thu 22 Aug Times are displayed in time zone: (GMT+02:00) Amsterdam, Berlin, Bern, Rome, Stockholm, Vienna change
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Richard A. EisenbergBryn Mawr College, USA