functional programming - Elm: understanding foldp and mouse-clicks -


i'm learning elm. relatively new functional programming. i'm trying understand example http://elm-lang.org/learn/using-signals.elm on counting mouse-clicks. provide following code: 

clickcount =     foldp (\click count -> count + 1) 0 mouse.clicks

they explain foldp takes 3 arguments: counter-incrementer, defined anonymous function 2 inputs, starting state 0, , mouse.clicks signal.

i not understanding why need variable click in our anonymous function. why can't have \count -> count + 1? input getting bound 1 of our inputs foldp?

thanks!

you need because foldp expects function 2 inputs. in case, first input ignored lambda, foldp implementation still puts in there. mouse.clicks puts sort of do-nothing value called unit in there.

some signals have value associated them, mouse.position, example. if wanted measure how far mouse has moved, need use parameter.


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