Hello, I have a function with type f :: Int -> Int -> Int -> Int -> Int -> NRup -> NRdown and I want to make sure it is evaluated only once for the same set of arguments but I observe that it is always evaluated several times. f is implemented in C and called via the FFI. The C function may or may not be pure. In principle it is but it is convenient to keep some state for debugging and monitoring. Anyway, even if it is pure, I want it to evaluate only once for a set of arguments because of performance. How can I enforce this? Is there a GHC option for that? Is there a way to write the Haskell code to achieve this? I have asked the same question in the context of FFI, but now it seems to me this question is not directly related to the FFI. Any hints? Thanks, Axel -- Phone: +46 8 790 4124, Email: axel@kth.se, Web: www.it.kth.se/~axel -- --- Phone: +46 8 790 4124, Email: axel@imit.kth.se, Web: www.imit.kth.se/~axel