Type parameters reversed about ploeh.github.com HOT 2 CLOSED

Yes, they're reversed. No, this is (unfortunately) not an error.

Languages (OCaml, F#) that call the type Result put the OK or Success case first (i.e. to the left) and the Error case second (i.e. to the right).

Languages (like Haskell) that call the type Either put the Left case first (because, well, that's to the left) and the Right case second (to the right). Inherently, Left and Right carry no additional semantics, but by convention (or, by pun), Right is used for those results that are... well, right (i.e. correct), which leaves the Left case for errors.

I usually follow that convention for both schools, which do, however, have the unfortunate power to confuse the careful reader.

FWIW, I usually favour the Either terminology, but there was a reason I adopted the Result terminology in the video. This is more evident if you watch the video, but basically, it's because I could explain how to arrive at the type gradually, via a series of refactorings from more specific Church-encoded types.

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Oh, no! Thanks for the clarification :)

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