Package org.apache.groovy.runtime

Class Comprehensions

java.lang.Object
org.apache.groovy.runtime.Comprehensions
@Incubating public final class Comprehensions extends Object
Runtime bind/map dispatcher for monadic comprehensions — the emit target of the DO macro.

The macro runs at SEMANTIC_ANALYSIS, before type checking, so it cannot know the carrier's bind-method name and cannot emit it directly. Instead it emits Comprehensions.bind(carrier) { x -> ... } calls; this class resolves the carrier-specific method at runtime (dynamic Groovy), while the groovy.typecheckers.MonadicChecker type-checking extension specialises this one signature under @CompileStatic.

This is runtime support invoked from generated bytecode, hence its placement in core alongside the rest of the Groovy runtime; the DO macro and the type checker are compile-time only and remain in their optional modules.

Participation is resolved first-match-wins:

  1. standard allow-list (MonadicCarrierRegistry);
  2. structural (flatMap/map present);
  3. @Monadic opt-in (matched by simple name; honours bind/map overrides).
A configured marker interface is a further opt-in mechanism that is not yet implemented.

Surface generosity: the carrier's bind method may accept a Function or a Closure; the closure is adapted to whichever the target declares. Monad laws are not enforced — structural participation, algebraic-law obligation on the implementer (the @Reducer/@Associative treatment).

Since:
6.0.0

  • Method Details

    • bind

      public static Object bind(Object carrier, Closure<?> fn)
      Bind (flatMap-shaped): carrier.<bind>(x -> fn(x)) where fn yields the same carrier.

    • map

      public static Object map(Object carrier, Closure<?> fn)
      Map: carrier.<map>(x -> fn(x)) where fn yields a plain value.