How to understand arrows!

Allow me to translate these function definitions into what they really are!

(>>>) :: a b c -> a c d -> a b d
  (>>>) :: (b -> c) -> (c -> d) -> (b -> d)

first :: a b c -> a (b, d) (c, d)
  first :: (b -> c) -> ((b, d) -> (c, d))

Yes, functions are arrows, that's why this works!

Knowing this is really good when you are doing random numbers:
random = first (\ n -> ...) . next
Look up the specifications and you'll see that random (in the class Random) should take a RandomGen and return (x, g) where x is the random value and g is the generator.  next returns a similar pair with an int and the new generator that should be returned.

It's magic I'm telling you!

ARROWS ARE REALLY USEFUL, CHECK THIS MINDHACK OUT


Prelude Control.Arrow> (snd &&& fst) (1,2)
(2,1)

WOOHOO!

Forced arbitrary of syntax, thread over.

>>3
infact scap that, the whole language is arbitrary.

*̡͌l̡*̡̡ ̴̡ ı̴̴ ̡̡|̲͡ ̲▫̲͡ ̲͡ π̲͡ ̲͡▫̲͡ ̲ ̲͡▫̲͡ ̲ ̲͡▫̲͡ ̲ ̲͡▫̲͡▫̲͡ ̲|̡̡ ̡ ̡ ̴̡ ı̴̴ ̡*̡͌l̡*

LISP

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