Proposal: add `Proxy`fied versions of `bitSizeMaybe` and `finiteBitSize`

[Simon Peyton Jones]

Now that we have visible type application, we could stop using these Proxy arguments, thus

	class Bits a where
 	  ...
	  bitSizeMaybe' :: Maybe Int

And you invoke it by saying
	bitSizeMaybe @ T
rather than 
	bitSizeMaybe (Proxy :: Proxy T)

Looks like a straight win to me.

Simon

|  -----Original Message-----
|  From: Libraries [mailto:libraries-bounces at haskell.org] On Behalf Of M
|  Farkas-Dyck
|  Sent: 14 December 2017 03:48
|  To: libraries at haskell.org
|  Subject: Proposal: add `Proxy`fied versions of `bitSizeMaybe` and
|  `finiteBitSize`
|  
|  I propose to add the following methods to `Bits` and `FiniteBits`
|  classes:
|  
|  class Bits a where
|       ...
|  
|       bitSizeMaybe' :: Proxy a -> Maybe Int
|  
|  class FiniteBits b where
|       ...
|  
|       finiteBitSize' :: Proxy b -> Int
|  
|  Rationale: working with an arbitrary `Bits a => a`, one may not have a
|  value of type `a` as argument to `bitSizeMaybe` or `finiteBitSize`,
|  and writing `undefined` makes me feel dirty.
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