Re: bind :: Monad m => (a -> m b) -> m a -> m b

I don't really understand why people want this. What's wrong with (=<<) ? I kind of feel like a named function should be no longer than that. I don't object, especially if others think it's useful (and many clearly do), but I guess it's not to my taste. On 08:02, Wed, Dec 10, 2014 David Feuer wrote:

joinMap looks to me like the best name, because it does just what it says on the box:

join . fmap f $ m = (m >>= return . f) >>= id --Functor/Monad law = m >>= (\x -> return (f x) >>= id) --associativity = m >>= (\x -> f x) --left identity = m >>= f --eta reduction = f =<< m Christopher Done writes:

...

Is this defined anywhere in base, and if not could it be placed in Control.Monad? I often find myself writing:

fmap (mu bar) (foo zot)

Then I decide to change the type of x, so instead I want to just write:

bind (mu bar) (foo zot)

Which is just like fmap but the function can run in the monad. Similar to traverse:

(Traversable t, Applicative f) => (a -> f b) -> t a -> f (t b)

As someone who isn’t a fan of operators, I generally am appreciative of alternative regular plain English word versions of functions, which I find easier to type, read and edit. Currently without defining such a handy name, I have to transform the code to this:

mu bar =<

The name for this function is a no-brainer:

bind :: Monad m => (a -> m b) -> m a -> m bbind = (=<<)

I'm -1 on the *name* `bind`, because as others have mentioned, I feel bind has the same type as (>>=).

That said, I'm +1 on the *idea* - if we can find a better name. `joinMap` doesn't seem too bad, as was recently suggested, but I'll settle on anything other than `bind`

-- ocharles

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