Re: [Haskell-cafe] Coercible between data A a b = A a b and (a, b)

Hello Oleg, Is there a good, somewhat up-to-date source of reference to find out what exactly is different? Is it the STG paper from 1992 (“Implementing lazy functional languages on stock hardware”)? -- Best wishes, Artem Pelenitstyn On Mon, 25 Feb 2019 at 10:17 Oleg Grenrus wrote:

Two data types are `Coercible` (as in Data.Coerce) if their representation in memory is the same: they are representiationally equivalent You ask for looser structural isomorphism, consider e.g.

data B b = B {-# UNPACK #-} !Int b

and

(Int, b)

The values of these types have quite different representation/memory layout.

- Oleg

On 25 Feb 2019, at 16.38, Georgi Lyubenov wrote:

Greetings!

Is there any reason behind/what is the reason behind ``` data A a b = A a b ``` and ``` (a, b) ```

not being coercible?

And in general all n-ary constructors not being coercible to one another?

Thanks in advance!

======= Georgi

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