2006/1/10, [EMAIL PROTECTED] <[EMAIL PROTECTED]>: > It seems using types to enforce the policy that a data base handle > cannot ever `leak' out might be a better idea, in Haskell. It is quite > straight-forward to do so: cf. the design of the ST monad guarantees > that an STRef cannot `leak' out in the result of runST. Monadic > Regions (implemented in Haskell) generalize the idea to multiple > nested regions: a pointer (or any other resource, e.g., a database > cursor) allocated in one region can be used in nested regions but > cannot leak outside of the region that created it (Or, to be more > precise, cannot be used outside -- and so, can be safely deallocated > when the region is exited).
This might be a good idea. > Incidentally, the difficulty with finalizers was precisely the > argument for using enumerators rather than cursors in database > APIs. Takusen has implemented that idea; takusen currently supports > Sqlite, PostgreSQL and Oracle, has a test suite. Its performance test > shows that takusen can retrieve 2 million rows from a table without > running out of memory. Can you explain how do you manage the lifetime of handles in Takusen? It isn't clear to me where are the advantages of enumerators. Krasimir _______________________________________________ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell
