functor

In an interview they asked me if using function pointers would be beneficial (in terms of speed) when writing code for embedded systems? I had no idea on embedded system so could not answer the question. Just a cloudy or vague answer. So what are the real benefits? Speed, readability, maintenance,cost? I think perhaps Viren Shakya's answer misses the point that the interviewer was trying to elicit. In some constructs the use of a function pointer may speed up execution. For example, if you have an index, using that to index an array of function pointers may be faster than a large switch. If

Today I wanted to investigate if it is possible to construct a data type in such a way, that it does not store the data of the type of its type signature, but another representation of it. So, here is my attempt of an GADT which has a type constructor of type a , but a data constructor of type ByteString . {-# LANGUAGE GADTs #-} import Data.ByteString.Char8 import Data.Serialize data Serialized a where MkSerialized :: (Serialize a) => ByteString -> Serialized a Now I can define a decode' function in the following way: decode' :: (Serialize a) => Serialized a -> a decode' (MkSerialized bs) =

How can I make (a, a) a Functor without resorting to a newtype ? Basically I want it to work like this: instance Functor (a, a) where fmap f (x, y) = (f x, f y) But of course that's not a legal way to express it: Kind mis-match The first argument of `Functor' should have kind `* -> *', but `(a, a)' has kind `*' In the instance declaration for `Functor (a, a)' What I really want is a type-level function like this: \a -> (a, a) (invalid syntax). So a type alias, perhaps? type V2 a = (a, a) instance Functor V2 where fmap f (x, y) = (f x, f y) I would think this would work, but it doesn't. First I

the type of fmap in Functor is: fmap :: Functor f => (a -> b) -> f a -> f b it looks like ,first apply function (a -> b) to the parameter of f a to create a result of type b, then apply f to it, and result is f b using Maybe a for example : fmap show (Just 1) result is : Just "1" same as saying: Just (show 1) but when (->) is used as a Functor (in Control.Monad.Instances) import Control.Monad.Instances (fmap show Just) 1 result is : "Just 1" that is, Just is apply first, then show is applied. in another example ,result is same: fmap (*3) (+100) 1 result is 303 why not *3 first, then +100? the

Can ML functors be practically expressed with .NET interfaces and generics? Is there an advanced ML functor use example that defies such encodings? Answers summary : In the general case, the answer is NO. ML modules provide features (such as specification sharing via signatures [ 1 ]) that do not directly map to .NET concepts. However, for certain use cases the ML idioms can be translated. These cases include not only the basic Set functor [ 2 ], but also the functorial encoding of monads [ 3 ], and even more advanced uses of Haskell, such as finally tagless interpreters [ 4 , 5 ]. Practical