<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div><div style="direction: inherit;"><span style="background-color: rgba(255, 255, 255, 0);">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. </span></div><div style="direction: inherit;"><span style="background-color: rgba(255, 255, 255, 0);"><br></span></div><div style="direction: inherit;"><span style="background-color: rgba(255, 255, 255, 0);"> data B b = B {-# UNPACK #-} !Int b</span></div><div style="direction: inherit;"><span style="background-color: rgba(255, 255, 255, 0);"><br></span></div><div style="direction: inherit;">and</div><div style="direction: inherit;"><br></div><div style="direction: inherit;"> (Int, b)</div><div style="direction: inherit;"><br></div><div style="direction: inherit;">The values of these types have quite different representation/memory layout.</div><div style="direction: inherit;"><br></div><div style="direction: inherit;">- Oleg</div></div><div><br>On 25 Feb 2019, at 16.38, Georgi Lyubenov <<a href="mailto:godzbanebane@gmail.com">godzbanebane@gmail.com</a>> wrote:<br><br></div><blockquote type="cite"><div><div dir="ltr">Greetings!<br><br>Is there any reason behind/what is the reason behind<br>```<br>data A a b = A a b<br>```<br>and<br>```<br>(a, b)<br>```<br><br>not being coercible?<br><br>And in general all n-ary constructors not being coercible to one another?<br><br>Thanks in advance!<div><br>=======<br>Georgi</div></div>
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