December Meetup: A More General Type For \f x -> f (f x)

Galois will be providing food and drinks at 6:30pm. Talk will start at 7:00pm.

Noah Easterly will give a talk titled "A More General Type For \f x -> f (f x)".

In Haskell, even a simple numeric literal has the polymorphic type of `Num a => a`, so it's no surprise that GHC can infer a polymorphic type for function literals like `\f x -> f (f x)`. During this talk, we'll demonstrate other possible types for `\f x -> f (f x)`, show that they're incompatible with the compiler inferred type, and then construct a more general type that unifies with all of these. This talk assumes only a basic knowledge of Haskell types, but will cover topics including higher-rank types, type unification/specialization, and defunctionalization.