erlang: proplists module (get_value/get_all_values/is_defined/lookup/delete) (874/874)

proplists BIFs in lib/erlang/lists-ext.sx (now lists + proplists).
Bare-atom shorthand {A,true}, first-match lookups, get_value default
undefined, lookup -> tuple | none. lists_ext suite 91 -> 103.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lib/erlang/lists-ext.sx

@@ -1,4 +1,4 @@
-;; lib/erlang/lists-ext.sx — extra `lists` module BIFs.
+;; lib/erlang/lists-ext.sx — extra stdlib BIFs (`lists` + `proplists`).
 ;;
 ;; Loaded AFTER runtime.sx so the BIF registry + transpile helpers
 ;; (er-mk-cons, er-lt?, er-equal?, er-bool, er-truthy?, er-apply-fun,
@@ -558,6 +558,114 @@
   er-bif-lists-search
   (fn (vs) (er-ext-search (nth vs 0) (nth vs 1))))
 
+;; ── proplists module ──────────────────────────────────────────────
+;; A property list element is either a bare atom A (shorthand for
+;; {A, true}) or a tuple whose first element is the key (value = its
+;; second element, or true for a 1-tuple). Lookups use the FIRST match.
+(define
+  er-ext-pl-key-of
+  (fn (e)
+    (cond
+      (er-atom? e) e
+      (and (er-tuple? e) (>= (len (get e :elements)) 1)) (nth (get e :elements) 0)
+      :else nil)))
+
+(define
+  er-ext-pl-val-of
+  (fn (e)
+    (cond
+      (and (er-tuple? e) (>= (len (get e :elements)) 2)) (nth (get e :elements) 1)
+      :else (er-mk-atom "true"))))
+
+(define
+  er-ext-pl-match?
+  (fn (key e)
+    (let ((k (er-ext-pl-key-of e)))
+      (and (not (= k nil)) (er-equal? key k)))))
+
+(define
+  er-ext-pl-get-value
+  (fn (key lst default)
+    (cond
+      (er-nil? lst) default
+      (er-cons? lst)
+        (if (er-ext-pl-match? key (get lst :head))
+          (er-ext-pl-val-of (get lst :head))
+          (er-ext-pl-get-value key (get lst :tail) default))
+      :else default)))
+
+(define
+  er-bif-pl-get-value
+  (fn (vs)
+    (cond
+      (= (len vs) 2)
+        (er-ext-pl-get-value (nth vs 0) (nth vs 1) (er-mk-atom "undefined"))
+      (= (len vs) 3)
+        (er-ext-pl-get-value (nth vs 0) (nth vs 1) (nth vs 2))
+      :else (error "Erlang: proplists:get_value: wrong arity"))))
+
+(define
+  er-ext-pl-all
+  (fn (key lst acc)
+    (cond
+      (er-nil? lst) (er-list-reverse-iter acc (er-mk-nil))
+      (er-cons? lst)
+        (er-ext-pl-all key (get lst :tail)
+          (if (er-ext-pl-match? key (get lst :head))
+            (er-mk-cons (er-ext-pl-val-of (get lst :head)) acc)
+            acc))
+      :else (er-list-reverse-iter acc (er-mk-nil)))))
+
+(define
+  er-bif-pl-get-all-values
+  (fn (vs) (er-ext-pl-all (nth vs 0) (nth vs 1) (er-mk-nil))))
+
+(define
+  er-ext-pl-defined?
+  (fn (key lst)
+    (cond
+      (er-nil? lst) false
+      (er-cons? lst)
+        (if (er-ext-pl-match? key (get lst :head))
+          true
+          (er-ext-pl-defined? key (get lst :tail)))
+      :else false)))
+
+(define
+  er-bif-pl-is-defined
+  (fn (vs) (er-bool (er-ext-pl-defined? (nth vs 0) (nth vs 1)))))
+
+(define
+  er-ext-pl-lookup
+  (fn (key lst)
+    (cond
+      (er-nil? lst) (er-mk-atom "none")
+      (er-cons? lst)
+        (if (er-ext-pl-match? key (get lst :head))
+          (let ((e (get lst :head)))
+            (if (er-tuple? e) e (er-mk-tuple (list e (er-mk-atom "true")))))
+          (er-ext-pl-lookup key (get lst :tail)))
+      :else (er-mk-atom "none"))))
+
+(define
+  er-bif-pl-lookup
+  (fn (vs) (er-ext-pl-lookup (nth vs 0) (nth vs 1))))
+
+(define
+  er-ext-pl-delete
+  (fn (key lst)
+    (cond
+      (er-nil? lst) (er-mk-nil)
+      (er-cons? lst)
+        (if (er-ext-pl-match? key (get lst :head))
+          (er-ext-pl-delete key (get lst :tail))
+          (er-mk-cons (get lst :head) (er-ext-pl-delete key (get lst :tail))))
+      :else lst)))
+
+(define
+  er-bif-pl-delete
+  (fn (vs) (er-ext-pl-delete (nth vs 0) (nth vs 1))))
+
 ;; ── register ──────────────────────────────────────────────────────
 ;; Hook into er-register-builtin-bifs! rather than registering once:
 ;; the registry can be reset + rebuilt mid-run (tests/runtime.sx does
@@ -594,7 +702,13 @@
     (er-register-pure-bif! "lists" "flatmap" 2 er-bif-lists-flatmap)
     (er-register-pure-bif! "lists" "filtermap" 2 er-bif-lists-filtermap)
     (er-register-pure-bif! "lists" "mapfoldl" 3 er-bif-lists-mapfoldl)
-    (er-register-pure-bif! "lists" "search" 2 er-bif-lists-search)))
+    (er-register-pure-bif! "lists" "search" 2 er-bif-lists-search)
+    (er-register-pure-bif! "proplists" "get_value" 2 er-bif-pl-get-value)
+    (er-register-pure-bif! "proplists" "get_value" 3 er-bif-pl-get-value)
+    (er-register-pure-bif! "proplists" "get_all_values" 2 er-bif-pl-get-all-values)
+    (er-register-pure-bif! "proplists" "is_defined" 2 er-bif-pl-is-defined)
+    (er-register-pure-bif! "proplists" "lookup" 2 er-bif-pl-lookup)
+    (er-register-pure-bif! "proplists" "delete" 2 er-bif-pl-delete)))
 
 (define er-ext-prev-register-builtins er-register-builtin-bifs!)
 (define er-register-builtin-bifs!