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new 9aa78ee add PurityChecker
9aa78ee is described below
commit 9aa78eef3674ae0ba448160ee199662cacd3f62d
Author: Paul King <[email protected]>
AuthorDate: Fri Apr 10 15:00:08 2026 +1000
add PurityChecker
---
site/src/site/releasenotes/groovy-6.0.adoc | 47 ++++++++++++++++++++++++++++++
1 file changed, 47 insertions(+)
diff --git a/site/src/site/releasenotes/groovy-6.0.adoc
b/site/src/site/releasenotes/groovy-6.0.adoc
index 5cee594..09fbc22 100644
--- a/site/src/site/releasenotes/groovy-6.0.adoc
+++ b/site/src/site/releasenotes/groovy-6.0.adoc
@@ -895,6 +895,53 @@ which is where AI starts hallucinating or saying "I'd need
to see more context."
| Must trace `auditLog` usage everywhere
|===
+=== PurityChecker
+
+The `PurityChecker` type checking extension
+(https://issues.apache.org/jira/browse/GROOVY-11914[GROOVY-11914])
+enforces functional purity at compile time. It verifies that methods
+annotated with `@Pure` have no side effects -- no field mutations,
+no I/O, no non-determinism -- and reports violations as compile errors.
+
+[source,groovy]
+----
+@TypeChecked(extensions = 'groovy.typecheckers.PurityChecker')
+class ScoreCalculator {
+ int bonus = 10
+
+ @Pure
+ int doubled() { bonus * 2 } // ok: reads only
+
+ @Pure
+ int increment() { bonus++; bonus } // compile error: @Pure violation
— field assignment
+}
+----
+
+The checker also recognises `@SideEffectFree`, `@Contract(pure = true)`,
+and `@Memoized` as effectively pure, and warns when a pure method calls
+an unchecked method whose purity cannot be verified.
+
+Since some "impure" operations are routine in practice,
+the checker accepts an `allows` parameter to selectively permit
+specific categories of side effects:
+
+[source,groovy]
+----
+@TypeChecked(extensions = 'groovy.typecheckers.PurityChecker(allows:
"LOGGING|METRICS")')
+class GameEngine {
+ @Pure
+ int computeScore(int base) {
+ println "computing score" // ok: LOGGING allowed
+ base * 2
+ }
+}
+----
+
+The configurable categories are `LOGGING` (println, SLF4J, JUL, Log4j),
+`METRICS` (Micrometer, OpenTelemetry), `IO` (file, network, database),
+and `NONDETERMINISM` (random, time-dependent calls).
+This is another example of parameterized type checking extensions in action.
+
== Platform Logging
Groovy 6 replaces direct `System.err` output with the JDK's
