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Agree. Haskellers call them lenses.<br>
<br>
There was a discussion about them here a few years ago:<br>
<br>
<a class="moz-txt-link-freetext" href="http://erlang.org/pipermail/erlang-questions/2015-November/086879.html">http://erlang.org/pipermail/erlang-questions/2015-November/086879.html</a><br>
<br>
And there have been a few implementation attempts:<br>
<br>
2020 <a class="moz-txt-link-freetext" href="https://github.com/slepher/lenses">https://github.com/slepher/lenses</a><br>
2015 <a class="moz-txt-link-freetext" href="https://www.cs.otago.ac.nz/staffpriv/ok/lens.erl">https://www.cs.otago.ac.nz/staffpriv/ok/lens.erl</a><br>
2012 <a class="moz-txt-link-freetext" href="https://github.com/jlouis/erl-lenses">https://github.com/jlouis/erl-lenses</a><br>
<br>
Best wishes<br>
<br>
Ivan<br>
<br>
<br>
<div class="moz-cite-prefix">On 16/06/2021 03:04, 瀬川昂弘 wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAPqsYP+xxt-VxwXudTPsuY1=KXqQ6wTfUe=H6mB=96zvj+V5-A@mail.gmail.com">
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<div>Assuming,</div>
<div>Map = <span
style="color:rgb(0,0,0);font-family:Menlo;font-size:11px">#{a
=> b,c => #{1 => 2,3 => 4,5 => #{x =>
y}}}.</span></div>
<div><br>
</div>
<div><font face="Menlo" color="#000000"><span
style="font-size:11px">Expected:</span></font></div>
<div><font face="Menlo" color="#000000"><span
style="font-size:11px"><a class="moz-txt-link-freetext" href="maps:new_find_fun(Key">maps:new_find_fun(Key</a> = 5, Map)
= {ok,</span></font><span
style="color:rgb(0,0,0);font-family:Menlo;font-size:11px">#{x
=> y}</span><span
style="font-size:11px;color:rgb(0,0,0);font-family:Menlo">}.</span><br>
</div>
<div><br>
</div>
<div><font face="Menlo" color="#000000"><span
style="font-size:11px">It's useful there is the above
feature, in my guess.</span></font></div>
<div><br>
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-- <br>
<div dir="ltr" class="gmail_signature">
<div dir="ltr">Takahiro Segawa.<br>
E-mail：<span><a
href="mailto:123430024@ccalumni.meijo-u.ac.jp"
target="_blank" moz-do-not-send="true">123430024@ccalumni.meijo-u.ac.jp</a></span><br>
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</blockquote>
<br>
<pre class="moz-signature" cols="72">--
============================================================
Ivan A. Uemlianin PhD
Llaisdy
Ymchwil a Datblygu Technoleg Lleferydd
Speech Technology Research and Development
<a class="moz-txt-link-abbreviated" href="mailto:ivan@llaisdy.com">ivan@llaisdy.com</a>
@llaisdy
llaisdy.wordpress.com
github.com/llaisdy
<a class="moz-txt-link-abbreviated" href="http://www.linkedin.com/in/ivanuemlianin">www.linkedin.com/in/ivanuemlianin</a>
festina lente
============================================================</pre>
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