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Showing posts from June, 2007

Objects are Existential Packages

There's a long-running debate on the power of functional languages over object-oriented languages. In truth, now that C# has full generics, aka parametric polymorphism, it's almost equivalent in typing power to most typical statically typed functional languages. In fact, in terms of typing power, generic objects are universal and existential types, and can be used for all the fancy static typing trickery that those entail (see my previous reference to the GADTs in C# to see what I mean).

As a prior post explained, C#'s type system still lacks some of the flexible constraint refinement available in more powerful functional type systems, but in general C# is powerful enough to encode most interesting functional abstractions.

And I started a new project to demonstrate this: FP#. It provides a number of widely used functional abstractions, like the option type, a lazy type, lists, lazy lists, etc. and map, filter, and fold over all the collection types, including the standard …