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Things I figured out about Haskell today
- Maybe is the same thing as Kleene ? (the "zero or one" operator in regular expressions).
- A typeclass is the same thing as an STL concept, but a typeclass actually means it.
- instance means "We're going to make this data type an instance of this typeclass, and here's how."
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An element of an object in a nice category - say, for instance a data type in an appropriate category of data types and computable functions - is a computable function from the terminal object (to which there is one unique map from every other object) to your object.
So, in Haskell terms, an element is just a 0-ary function
1 :: () -> Int
and then the compiler is gracious enough to give us syntax sugar for 0-ary functions.