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clarify

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This commit is contained in:
Adam Jeniski
2026-09-14 08:55:02 -09:00
parent cafc844708
commit d550f03602
1 changed files with 23 additions and 9 deletions
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learnclj.clj
+23 -9
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@@ -263,27 +263,41 @@ nil ; => nil (Null/Nothing)
;; --- 14. Java Interop --- ;; --- 14. Java Interop ---
;; Method call ;; === Method Calls ===
;; Direct form: (. object methodName args…)
(.toUpperCase "hello") ; => "HELLO" (.toUpperCase "hello") ; => "HELLO"
(.substring "hello" 1 3) ; => "el" (.substring "hello" 1 3) ; => "el"
;; Field form: (. object fieldName) — for getters (no args)
(. "hello" length) ; => 5 (. "hello" length) ; => 5
(.length "hello") ; => 5
(.age alice) ; => 30 (.age alice) ; => 30
;; Dot-dot (..): chained field access + method call
(.. alice email toUpperCase) ; => "ALICE@EXAMPLE.COM" (.. alice email toUpperCase) ; => "ALICE@EXAMPLE.COM"
;; Equivalent to: (. (. alice email) toUpperCase)
;; Static method ;; === Static Methods ===
(System/getProperty "user.name") ; => "ajet"
;; Constructor ;; (Class/fieldName) or (Class/staticMethod args…)
(System/getProperty "user.name") ; => "ajet" (static field/property)
(System/getProperty "java.version") ; => "21.0.x" (static method call)
;; === Constructors ===
;; (Class.) or (Class. arg1 arg2…)
(java.util.Date.) ; => #inst "2026-09-14T..." (current date/time) (java.util.Date.) ; => #inst "2026-09-14T..." (current date/time)
(java.util.Date. 2024 0 1) ; => #inst "2024-01-01T..."
;; --- 15. Threading Macros --- ;; --- 15. Threading Macros ---
;; Thread-first (->) — passes result as first arg ;; Thread-first (->) — passes result as first arg
;; Note: (.method args) inside -> is a method call on the threaded value
(-> "hello" (-> "hello"
(.toUpperCase) (.toUpperCase) ; method call: .toUpperCase on "hello"
(.replace "H" "J") (.replace "H" "J") ; method call: .replace on "HELLO"
(.toLowerCase)) ; => "jello" (.toLowerCase)) ; method call: .toLowerCase on "JELLO"
; => "jello"
;; Thread-last (->>) — passes result as last arg ;; Thread-last (->>) — passes result as last arg
(->> [1 2 3 4 5] (->> [1 2 3 4 5]
@@ -297,7 +311,7 @@ nil ; => nil (Null/Nothing)
(try (try
(/ 1 0) (/ 1 0)
(catch ArithmeticException e (catch ArithmeticException e
(str "Math error: " (.getMessage e)))) ; => "Math error: Divide by zero" (str "Math error: " (.getMessage e)))) ; method call: (.getMessage e) => "Math error: Divide by zero"
;; assert — throws AssertionError on failure ;; assert — throws AssertionError on failure
(assert (= 2 (+ 1 1))) ; => nil (assert returns nil on success) (assert (= 2 (+ 1 1))) ; => nil (assert returns nil on success)