Type classes derivation : arrays (or varargs) are problematic

[gneuvill]

Ex:

@Data @Derive(@Instances(Equal.class))
public interface VThing {
   interface Cases<R> {
        R VThing(String... names); // or String[]
    }
   <R> R match(Cases<R> cases);
}

Behaviour : no instances is searched after (because in DeriveUtilsImpl.instanceInitializer, instance resolution is conditioned by the arg. type being a DeclaredType, which ArrayType are not) ; consequently, uncompilable code gets generated

Current workaround : use a collection type for which instances can be resolved.

@jbgi Is this worth fixing ?

[jbgi]

Slightly improved via the last commits: see https://github.com/derive4j/derive4j/blob/master/examples/src/main/java/org/derive4j/example/ArrayWrapper.java#L21
But yeah, not sure if it's worth going any further: one should probably use immutable array wrappers anyway.