Why does `changes` return `Event t (Future a)`

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The changes function has type Frameworks t => Behavior t a -> Moment t (Event t (Future a)). Future is abstract and there is only one function that consumes it (reactimate').

However, I can easily write the following function:

changes' :: Frameworks t => Behavior t a -> Moment t (Event t a)
changes' b = fmap (fmap const b <@>) (changes b)

to get a normal (non-Future) event.

Is something wrong with that function? If not, why does the original changes function have a more restrictive type?

asked 34 secs ago

Tobias Brandt

1,661

Why does `changes` return `Event t (Future a)`