record-builder VS amber-docs

The problem with this approach is that the people will have to build crutches like https://github.com/Randgalt/record-builder and by the time Java adds missing features all the codebases will be forever polluted with legacy workarounds that nobody will dare to remove because of backwards compatibility.

It also hinders adoption of new features as people will prefer to maintain consistency in their codebases.

Record builder is pretty good for making builders for your Java 17 records

I always have to bring up RecordBuilder simply because of the included Withers and it being a source generator instead of the Lombok weirdness.

The above is not particularly user-friendly. Luckily compiler plugins can provide the missing feature, most notably RecordBuilder:

For records, instead of lombok you can use https://github.com/Randgalt/record-builder which is a valid annotation processor and will not break on JDK changes

In this particular case you can generate the builder with something like https://github.com/Randgalt/record-builder that is both valid java and lombok-like enough

Records + Record Builder or immutables + the trick to hide the implementing class w/sealed are your friend. Both the mutability and naming conventions this generates are vomitus.

Did you use https://github.com/Randgalt/record-builder ?

Try my annotation processor. It generates withers. https://github.com/Randgalt/record-builder

I personally don't use that one much, but you could use this library instead.

Record patterns are one step on the path to general pattern matching utility. The bigger building block is general deconstructors. I recommend reading Functional Transformation of Immutable Objects by Brian Goetz. The idea of "withers" shown there requires deconstructors:

https://github.com/openjdk/amber-docs/blob/master/eg-drafts/...

This is the vague plan.

You may be joking but...

Here is the much more detailed version: https://github.com/openjdk/amber-docs/blob/master/eg-drafts/reconstruction-records-and-classes.md

This kind of pattern matching is discussed in the design notes: https://github.com/openjdk/amber-docs/blob/master/site/design-notes/patterns/pattern-match-object-model.md

True, but that only pushes the question of value down the line.

I'm curious about lenses because Java did have a serious problem that required a solution: working with "simple" data correctly was difficult. The chosen solution was ADTs, so we did buy into that. But the approach being explored for transforming records (https://github.com/openjdk/amber-docs/blob/master/eg-drafts/...) only works one level at a time rather than for an entire path. So I wonder how valuable it would be to have a solution for paths. If the answer is that it's mostly valuable for an approach we haven't bought into yet, then we might not need to consider it just yet.

Just a heads up, something like that spread operator is actually coming sooner or later to java: https://github.com/openjdk/amber-docs/blob/master/eg-drafts/...

Pattern matching (for records) is already a preview feature.