Namespaces and Java

Namespaces

Bridje code is split into namespaces, one per file. A namespace’s name mirrors its path: todo.model lives in src/main/bridje/todo/model.brj, and starts with an ns: form:

ns: todo.model

decl: .doneBy Str

enum: Status
  tag: Open
  tag: Done{.doneBy}

decl: isDone(Status) Bool
def: isDone(status)
  case: status
    Done true
    false

Another namespace uses it by requiring it, under an alias:

ns: todo.app
  require:
    todo:
      as(model, m)

def: main(args)
  println(m/isDone(m/Done{.doneBy "me"}))

The require: block groups namespaces by their prefix: under todo:, as(model, m) means “todo.model, known here as m”. Everything todo.model defines is then available through the alias — m/isDone, m/Done, and for keys, m/.doneBy. If you don’t need a different alias, the bare name will do: require: brj: test gives you brj.test as test.

Within a namespace, definitions are read top to bottom, and a definition can only use what’s defined above it. So a Bridje file reads from the bottom up: small helpers first, the functions that use them after.

Java

Bridje runs on the JVM, and every Java library is available to it. Importing a class gives it an alias, much as requiring a namespace does:

ns: todo.app
  import:
    java.time:
      as(Instant, Instant)

Static methods are called through the alias:

Instant/now()

For Bridje to type-check calls into Java, you declare the members you use, in Bridje’s own syntax:

decl: Instant/now() Instant
decl: Instant/.toEpochMilli() Int

Instant/now() is a static method taking nothing and returning an Instant. Instant/.toEpochMilli() — with the dot — is an instance method, so it’s called with the instance as its first argument:

Instant/.toEpochMilli(Instant/now())
// => 1790530653092

The declarations are yours to get right: Bridje trusts them. Some of the standard library, like brj.time, is exactly this — Java classes with Bridje declarations over the top.

That’s the tour

You’ve now seen most of what Bridje looks like: expressions and blocks, functions, records, tags and enums, effects, namespaces and Java.

From here:

• the reference covers every form in detail;
• About Bridje explains the thinking behind the design;
• and idioms is a short guide to writing Bridje the way it’s meant to be written.