Default names and explicit roles

Use a Vernac Maven project from the plugin tutorial. Create namespace example.naming, then a file within that namespace:

namespace example.naming;

id TaskId;
value Title(String);
value Reference(TaskId);

Run mvn compile. Inspect the generated sources: Title exposes string(), Reference exposes taskId(), and the ID exposes its fixed UUID getter value().

Choose your public API

Change the title declaration to:

value Title(String value);

Now its getter is value(). There is no second string() alias. Java callers must use the declared API. Explicit field names are useful domain documentation.

To see that field count does not affect defaults, try these alternative versions:

value Price(BigDecimal);

value Price(BigDecimal, Currency);

Both expose bigDecimal(). The second adds currency(). Prefer an explicit amount when that better expresses your domain.

Explain distinct roles

Add value Comparison(Title, Title);. Both fields would be called title, so Vernac rejects it. Correct it to:

value Comparison(Title previous, Title current);

Vernac will not invent title2. Different types can collide too: int and a VO named IntValue both produce intValue when used as unnamed fields.

Explore an API conflict

Try value Description(String toString);. The getter would collide with the promised toString() method. Use String text instead, provided that name is not already used in your declaration. The editor should show the same compiler error; if diagnostics seem outdated, check that the installed plugin contains the current language server.

FAQ

Why does my one-field VO no longer expose value() automatically? All ordinary fields follow one rule. Write the name value explicitly for a wrapper API. Adding another field then cannot silently rename the original getter.

Can a field be named equals? Yes, if otherwise valid: its getter equals() is distinct from equals(Object). Method signatures, not a global list of method names, determine collisions.

How are acronyms treated? URLValue gives urlValue, HTMLXMLMapper gives htmlxmlMapper, and HTML2XMLMapper gives html2XMLMapper. No dictionary is used. UrlValue is a recommended spelling; an explicit field name always takes precedence.

Does Vernac type-check my Java method body? Not as part of these checks. It checks the method declaration against the generated API. javac continues to check the embedded body.

See the names contract for exact rules.