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<div class="elementToProof" style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
Hello Valhalla community,</div>
<div class="elementToProof"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">I have reviewed the latest documents on the project and have some concerns about current
design decisions.</span></div>
<div class="elementToProof"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);"><br>
</span></div>
<div class="elementToProof"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">1) Implicit constructor cannot have body.</span></div>
<div class="elementToProof"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">While I understand why we need implicit ctor and why it must have no args, I still don't
understand why we can't allow users to set default values on their own using that ctor instead of implicitly defaulting them to (0, false, null). It could solve problems with such classes like LocalDate which require more special zeroInstance (1970-1-1) than
value with pure defaults.</span></div>
<div class="elementToProof"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">I believe that even String class could be somehow adopted to be value class in future
having default null-restricted value of "" with (byte[] value) assigned to empty byte array. Non-final fields (hash, hashIsZero) could be placed into separate final field (i.e. hashHolder) given that it will be forcedly flattened, so there will be no overhead. </span></div>
<div class="elementToProof" style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div class="elementToProof" style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
2) Implicit constructor must be public.</div>
<div class="elementToProof"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">We all learned that overextending public apis can lead to problems. Great example of
this is wrapper classes whose constructors have been deprecated long time ago and still causing a lot of problems. So, new classes (i.e. Optional) were designed to have static factories (Optional#of, Optional#empty), rather than exposing their internal constructors.
(Moreover, constructor calls use different byte-code instructions than method calls, which also can cause byte-code incompatibilities in case of future migrations.)</span></div>
<div class="elementToProof"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">I don't understand why we are going to make same mistake again and why we can't allow
implicit constructors to have any kind of visibility modifier. So, VM will be able to freely use zeroInstances where necessary, while user himself will be able to control use of class exposing special apis.</span></div>
<div class="elementToProof"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);"><br>
</span></div>
<div class="elementToProof"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">3) Using interface (LooselyConsistentValue) to express non-atomicness.</span></div>
<div class="elementToProof"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">Same story as with Serializable interface. It is considered that using marker-interface
for such a problem was bad design. Although this was justified by the fact that we did not have annotations, it is now unclear what makes us to use interfaces again. While it is possible to come up with real-life use cases of Serializable where type restrictions
may be required (some usage of ObjectI/OStream apis), for such VM-close features like non-atomicness there is no real need for such opportunity. (Moreover, we already have some inconveniences because of that. In some cases, type inference of "var" is already
blowing up from large type unions like Number & Comparable & Serializable.)</span></div>
<div class="elementToProof"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">So, I believe we should use alternatives like class modifier or annotation, rather than
polluting the type system for no reason. </span></div>
<div class="elementToProof"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);"><br>
</span></div>
<div class="elementToProof"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">Regards,</span></div>
<div class="elementToProof"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">Wilson.</span></div>
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