I\'m kind of new to Haskell and I\'m having a hard time understanding what is wrong with my code here.
Consider the following simple code to create a typesafe equals. This first section allows me to create an Identity typeclass for any type.
How can I make (a, a) a Functor without resorting to a newtype? Basically I want it to work like this:
Scala has a number of traits that you can use as type classes, for example Ordered and Numeric in the package scala.math.
I expected the following code to fail with a type error due to violation of the minBound and maxBound. But, as you can see, it goes through without flagging an error.
EDIT: Solved. I was unware that enabling a language extension in the source file did not enable the language extension in GHCi. The solution was to :set FlexibleContexts in GHCi.
I have the following typeclass which models a SQL-like query optimization: class OptimizableQuery q where
Hi I\'m looking for a quick example of type class usage in Scala that will work in both 2.7.7 and 2.8 environments.
Is it possible to emulate the type class functionality of Haskell with C++ (or C#) templates? Does it make sense or is there any payoff in doing that?
In scala, we can use implicit typeclasses to conditionally add methods onto a parameterized type dependent on that type\'s parameters. For example, Iterator.sum: