[Haskell-beginners] Expose every Function of a wrapped type

[鲍凯文]

Hi,

Have you considered using `Control.Lens.Wrapped` or `Control.Newtype`?
You'd have to move the wrapping/unwrapping bits to the sites in your code
at which you use underlying `Map` functions (quite repetitive), but it
could be easier than redefining all the functions you want (and definitely
easier than having to redefine a new one when you think of needing it?).

There's probably a canonical way to handle this sort of thing, but I can't
find it ATM. Good luck!

On Fri, Nov 15, 2019 at 5:00 AM <beginners-request at haskell.org> wrote:

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>    1.  Expose every Function of a wrapped type (Leonhard Applis)
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> Message: 1
> Date: Fri, 15 Nov 2019 11:36:03 +0000
> From: Leonhard Applis <Leonhard.Applis at protonmail.com>
> To: "beginners at haskell.org" <beginners at haskell.org>
> Subject: [Haskell-beginners] Expose every Function of a wrapped type
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> Hi,
>
> I currently have a newtype definition of a typed Data.Map.
>
> newtype G = G Data.Map String Values
>
> I have done this because for my specific use-case, I can define G as a
> monoid and get some nice benefits.
>
> However, I find myself often just re-declaring functions of Data.Map and
> wrap/unwrap them in my Constructor G, such as
>
> singleton :: String -> Value -> G
> singleton s v = G $ (Data.Map.singleton s v)
>
> I think I do not need to limit the scope of G's functionality, I basically
> want everything from Data.Map + Bonus , like my Monoid.
> Also I want G to be a specific Data.Map, there is never any other case
> where it's not a Map String Values.
>
> However, if I have
>
> type G2 = Data.Map String Values
>
> I cannot instance Monoid.
>
> So, I am very sure that I'm not the first person ever doing this. Is there
> a language extension providing what I want? Or is what i want "bad"?
> Am I just missing a higher-order base function which does what I want?
>
> best regards & thanks
> Leonhard
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