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Add java.util.Optional (#241)

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A value class libraries return from getters (java.time, and the java.net.http
client shim that aws-api's java backend builds on). Statics of/ofNullable/empty,
methods isPresent/isEmpty/get/orElse/orElseGet/ifPresent/toString, value-equal so
(= (Optional/of x) (Optional/of x)). Five JVM-certified corpus rows. Runtime .ss,
no re-mint.

Co-authored-by: Yogthos <yogthos@gmail.com>
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Dmitri Sotnikov 2026-06-26 20:08:23 +00:00 • committed by GitHub
parent 27d99db4bc
commit 301cda2e46
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27
host/chez/java/host-static-classes.ss
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@ -795,6 +795,33 @@
(cons "nextFloat" (lambda (self) (random 1.0)))
(cons "nextBoolean" (lambda (self) (fx=? 0 (random 2))))))
;; --- java.util.Optional -----------------------------------------------------
;; Returned by getters across java.time / java.net.http (e.g. HttpRequest.timeout,
;; HttpClient.connectTimeout). Value-equal so (= (Optional/of x) (Optional/of x)).
(define (jt-optional present? value) (make-jhost "optional" (vector present? value)))
(define jt-optional-empty (jt-optional #f jolt-nil))
(define (opt? x) (and (jhost? x) (string=? (jhost-tag x) "optional")))
(define (opt-present? o) (vector-ref (jhost-state o) 0))
(define (opt-value o) (vector-ref (jhost-state o) 1))
(let ((statics (list (cons "of" (lambda (v) (if (jolt-nil? v) (error #f "Optional.of(null)") (jt-optional #t v))))
(cons "ofNullable" (lambda (v) (if (jolt-nil? v) jt-optional-empty (jt-optional #t v))))
(cons "empty" (lambda _ jt-optional-empty)))))
(register-class-statics! "Optional" statics)
(register-class-statics! "java.util.Optional" statics))
(register-host-methods! "optional"
(list (cons "isPresent" (lambda (o) (opt-present? o)))
(cons "isEmpty" (lambda (o) (not (opt-present? o))))
(cons "get" (lambda (o) (if (opt-present? o) (opt-value o) (error #f "Optional.get() on empty Optional"))))
(cons "orElse" (lambda (o d) (if (opt-present? o) (opt-value o) d)))
(cons "orElseGet" (lambda (o f) (if (opt-present? o) (opt-value o) (jolt-invoke f))))
(cons "ifPresent" (lambda (o f) (when (opt-present? o) (jolt-invoke f (opt-value o))) jolt-nil))
(cons "toString" (lambda (o) (if (opt-present? o)
(string-append "Optional[" (jolt-str-render-one (opt-value o)) "]")
"Optional.empty")))))
(register-eq-arm! (lambda (a b) (or (opt? a) (opt? b)))
(lambda (a b) (and (opt? a) (opt? b) (eq? (opt-present? a) (opt-present? b))
(or (not (opt-present? a)) (jolt=2 (opt-value a) (opt-value b))))))
;; --- minimal JVM class/interface ancestry -----------------------------------
;; A handful of libraries reflect over the class hierarchy — e.g. core.memoize
;; validates its first argument with (some #{IFn AFn Runnable Callable}