diff --git a/lib/erlang/conformance.conf b/lib/erlang/conformance.conf
index 8aef90e6..9d5f2f67 100644
--- a/lib/erlang/conformance.conf
+++ b/lib/erlang/conformance.conf
@@ -33,6 +33,7 @@ SUITES=(
   "ffi:lib/erlang/tests/ffi.sx:{:passed er-ffi-test-pass :failed (- er-ffi-test-count er-ffi-test-pass) :total er-ffi-test-count}"
   "vm:lib/erlang/tests/vm.sx:{:passed er-vm-test-pass :failed (- er-vm-test-count er-vm-test-pass) :total er-vm-test-count}"
   "send_after:lib/erlang/tests/send_after.sx:{:passed er-sa-test-pass :failed (- er-sa-test-count er-sa-test-pass) :total er-sa-test-count}"
+  "lists_ext:lib/erlang/tests/lists_ext.sx:{:passed er-lx-test-pass :failed (- er-lx-test-count er-lx-test-pass) :total er-lx-test-count}"
 )
 
 # Preserve the historical scoreboard schema so consumers of
diff --git a/lib/erlang/runtime.sx b/lib/erlang/runtime.sx
index 4f379f10..46c2a569 100644
--- a/lib/erlang/runtime.sx
+++ b/lib/erlang/runtime.sx
@@ -2040,6 +2040,42 @@
       "duplicate"
       2
       er-bif-lists-duplicate)
+    (er-register-pure-bif! "lists" "sort" 1 er-bif-lists-sort)
+    (er-register-pure-bif! "lists" "sort" 2 er-bif-lists-sort)
+    (er-register-pure-bif! "lists" "usort" 1 er-bif-lists-usort)
+    (er-register-pure-bif! "lists" "keyfind" 3 er-bif-lists-keyfind)
+    (er-register-pure-bif! "lists" "keymember" 3 er-bif-lists-keymember)
+    (er-register-pure-bif! "lists" "keydelete" 3 er-bif-lists-keydelete)
+    (er-register-pure-bif! "lists" "keyreplace" 4 er-bif-lists-keyreplace)
+    (er-register-pure-bif! "lists" "keystore" 4 er-bif-lists-keystore)
+    (er-register-pure-bif! "lists" "keytake" 3 er-bif-lists-keytake)
+    (er-register-pure-bif! "lists" "keysort" 2 er-bif-lists-keysort)
+    (er-register-pure-bif! "lists" "foldr" 3 er-bif-lists-foldr)
+    (er-register-pure-bif! "lists" "partition" 2 er-bif-lists-partition)
+    (er-register-pure-bif! "lists" "takewhile" 2 er-bif-lists-takewhile)
+    (er-register-pure-bif! "lists" "dropwhile" 2 er-bif-lists-dropwhile)
+    (er-register-pure-bif! "lists" "splitwith" 2 er-bif-lists-splitwith)
+    (er-register-pure-bif! "lists" "flatten" 1 er-bif-lists-flatten)
+    (er-register-pure-bif! "lists" "max" 1 er-bif-lists-max)
+    (er-register-pure-bif! "lists" "min" 1 er-bif-lists-min)
+    (er-register-pure-bif! "lists" "zip" 2 er-bif-lists-zip)
+    (er-register-pure-bif! "lists" "zipwith" 3 er-bif-lists-zipwith)
+    (er-register-pure-bif! "lists" "unzip" 1 er-bif-lists-unzip)
+    (er-register-pure-bif! "lists" "sublist" 2 er-bif-lists-sublist)
+    (er-register-pure-bif! "lists" "sublist" 3 er-bif-lists-sublist)
+    (er-register-pure-bif! "lists" "nthtail" 2 er-bif-lists-nthtail)
+    (er-register-pure-bif! "lists" "split" 2 er-bif-lists-split)
+    (er-register-pure-bif! "lists" "droplast" 1 er-bif-lists-droplast)
+    (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! "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)
     (er-register-bif! "io" "format" 1 er-bif-io-format)
     (er-register-bif! "io" "format" 2 er-bif-io-format)
     (er-register-bif! "ets" "new" 2 er-bif-ets-new)
diff --git a/lib/erlang/scoreboard.json b/lib/erlang/scoreboard.json
index 614cd84c..cb709dc0 100644
--- a/lib/erlang/scoreboard.json
+++ b/lib/erlang/scoreboard.json
@@ -1,7 +1,7 @@
 {
   "language": "erlang",
-  "total_pass": 771,
-  "total": 771,
+  "total_pass": 874,
+  "total": 874,
   "suites": [
     {"name":"tokenize","pass":62,"total":62,"status":"ok"},
     {"name":"parse","pass":52,"total":52,"status":"ok"},
@@ -14,6 +14,7 @@
     {"name":"fib","pass":8,"total":8,"status":"ok"},
     {"name":"ffi","pass":37,"total":37,"status":"ok"},
     {"name":"vm","pass":78,"total":78,"status":"ok"},
-    {"name":"send_after","pass":10,"total":10,"status":"ok"}
+    {"name":"send_after","pass":10,"total":10,"status":"ok"},
+    {"name":"lists_ext","pass":103,"total":103,"status":"ok"}
   ]
 }
diff --git a/lib/erlang/scoreboard.md b/lib/erlang/scoreboard.md
index d3c00f8c..d8958028 100644
--- a/lib/erlang/scoreboard.md
+++ b/lib/erlang/scoreboard.md
@@ -1,6 +1,6 @@
 # Erlang-on-SX Scoreboard
 
-**Total: 771 / 771 tests passing**
+**Total: 874 / 874 tests passing**
 
 |  | Suite | Pass | Total |
 |---|---|---|---|
@@ -16,5 +16,6 @@
 | ✅ | ffi | 37 | 37 |
 | ✅ | vm | 78 | 78 |
 | ✅ | send_after | 10 | 10 |
+| ✅ | lists_ext | 103 | 103 |
 
 Generated by `lib/erlang/conformance.sh`.
diff --git a/lib/erlang/tests/lists_ext.sx b/lib/erlang/tests/lists_ext.sx
new file mode 100644
index 00000000..2e0fc806
--- /dev/null
+++ b/lib/erlang/tests/lists_ext.sx
@@ -0,0 +1,385 @@
+;; lists-ext tests — lists:sort/1, lists:sort/2, lists:usort/1.
+;; Each case evaluates an Erlang expression that reduces to the bool
+;; atom `true` (via =:= on the sorted result) and checks its name.
+
+(define er-lx-test-count 0)
+(define er-lx-test-pass 0)
+(define er-lx-test-fails (list))
+
+(define
+  er-lx-test
+  (fn
+    (name actual expected)
+    (set! er-lx-test-count (+ er-lx-test-count 1))
+    (if
+      (= actual expected)
+      (set! er-lx-test-pass (+ er-lx-test-pass 1))
+      (append! er-lx-test-fails {:name name :expected expected :actual actual}))))
+
+;; eval an Erlang source string and return the result atom's name
+(define er-lx-nm (fn (src) (get (erlang-eval-ast src) :name)))
+
+;; ── lists:sort/1 ──────────────────────────────────────────────────
+(er-lx-test "sort/1 ascending"
+  (er-lx-nm "lists:sort([3,1,2]) =:= [1,2,3]") "true")
+
+(er-lx-test "sort/1 already sorted"
+  (er-lx-nm "lists:sort([1,2,3]) =:= [1,2,3]") "true")
+
+(er-lx-test "sort/1 empty"
+  (er-lx-nm "lists:sort([]) =:= []") "true")
+
+(er-lx-test "sort/1 singleton"
+  (er-lx-nm "lists:sort([7]) =:= [7]") "true")
+
+(er-lx-test "sort/1 keeps duplicates"
+  (er-lx-nm "lists:sort([3,1,2,1]) =:= [1,1,2,3]") "true")
+
+(er-lx-test "sort/1 length preserved"
+  (erlang-eval-ast "length(lists:sort([5,4,3,2,1]))") 5)
+
+(er-lx-test "sort/1 term order: number < atom"
+  (er-lx-nm "lists:sort([b,a,1]) =:= [1,a,b]") "true")
+
+(er-lx-test "sort/1 tuples elementwise"
+  (er-lx-nm "lists:sort([{2,a},{1,b},{1,a}]) =:= [{1,a},{1,b},{2,a}]") "true")
+
+;; ── lists:sort/2 ──────────────────────────────────────────────────
+(er-lx-test "sort/2 ascending =<"
+  (er-lx-nm "lists:sort(fun(A,B) -> A =< B end, [3,1,2]) =:= [1,2,3]") "true")
+
+(er-lx-test "sort/2 descending >="
+  (er-lx-nm "lists:sort(fun(A,B) -> A >= B end, [1,3,2]) =:= [3,2,1]") "true")
+
+(er-lx-test "sort/2 stable on equal keys"
+  (er-lx-nm
+    "lists:sort(fun({A,_},{B,_}) -> A =< B end, [{1,x},{1,y},{0,z}]) =:= [{0,z},{1,x},{1,y}]")
+  "true")
+
+(er-lx-test "sort/2 empty"
+  (er-lx-nm "lists:sort(fun(A,B) -> A =< B end, []) =:= []") "true")
+
+;; ── lists:usort/1 ─────────────────────────────────────────────────
+(er-lx-test "usort/1 removes duplicates"
+  (er-lx-nm "lists:usort([3,1,2,1,3]) =:= [1,2,3]") "true")
+
+(er-lx-test "usort/1 empty"
+  (er-lx-nm "lists:usort([]) =:= []") "true")
+
+(er-lx-test "usort/1 all equal collapses to one"
+  (er-lx-nm "lists:usort([5,5,5]) =:= [5]") "true")
+
+(er-lx-test "usort/1 already unique"
+  (er-lx-nm "lists:usort([1,2,3]) =:= [1,2,3]") "true")
+
+(er-lx-test "usort/1 length after dedup"
+  (erlang-eval-ast "length(lists:usort([4,4,2,2,1,1,4]))") 3)
+
+;; ── lists:keyfind/3 ───────────────────────────────────────────────
+(er-lx-test "keyfind hit"
+  (erlang-eval-ast "element(2, lists:keyfind(b, 1, [{a,1},{b,2},{c,3}]))") 2)
+
+(er-lx-test "keyfind first match only"
+  (erlang-eval-ast "element(2, lists:keyfind(a, 1, [{a,1},{a,9}]))") 1)
+
+(er-lx-test "keyfind miss returns false"
+  (er-lx-nm "lists:keyfind(z, 1, [{a,1},{b,2}])") "false")
+
+(er-lx-test "keyfind on second element"
+  (er-lx-nm "element(1, lists:keyfind(2, 2, [{a,1},{b,2}]))") "b")
+
+(er-lx-test "keyfind skips short tuples"
+  (er-lx-nm "lists:keyfind(x, 2, [{x},{y,x}]) =:= {y,x}") "true")
+
+;; ── lists:keymember/3 ─────────────────────────────────────────────
+(er-lx-test "keymember true"
+  (er-lx-nm "lists:keymember(b, 1, [{a,1},{b,2}])") "true")
+
+(er-lx-test "keymember false"
+  (er-lx-nm "lists:keymember(z, 1, [{a,1},{b,2}])") "false")
+
+;; ── lists:keydelete/3 ─────────────────────────────────────────────
+(er-lx-test "keydelete removes first match"
+  (er-lx-nm "lists:keydelete(b, 1, [{a,1},{b,2},{c,3}]) =:= [{a,1},{c,3}]") "true")
+
+(er-lx-test "keydelete only first"
+  (er-lx-nm "lists:keydelete(a, 1, [{a,1},{a,2},{b,3}]) =:= [{a,2},{b,3}]") "true")
+
+(er-lx-test "keydelete miss unchanged"
+  (er-lx-nm "lists:keydelete(z, 1, [{a,1},{b,2}]) =:= [{a,1},{b,2}]") "true")
+
+;; ── lists:keyreplace/4 ────────────────────────────────────────────
+(er-lx-test "keyreplace hit"
+  (er-lx-nm
+    "lists:keyreplace(b, 1, [{a,1},{b,2},{c,3}], {b,99}) =:= [{a,1},{b,99},{c,3}]")
+  "true")
+
+(er-lx-test "keyreplace miss unchanged"
+  (er-lx-nm
+    "lists:keyreplace(z, 1, [{a,1}], {z,0}) =:= [{a,1}]") "true")
+
+;; ── lists:keystore/4 ──────────────────────────────────────────────
+(er-lx-test "keystore replaces existing"
+  (er-lx-nm
+    "lists:keystore(b, 1, [{a,1},{b,2}], {b,99}) =:= [{a,1},{b,99}]") "true")
+
+(er-lx-test "keystore appends when absent"
+  (er-lx-nm
+    "lists:keystore(z, 1, [{a,1},{b,2}], {z,0}) =:= [{a,1},{b,2},{z,0}]") "true")
+
+;; ── lists:keytake/3 ───────────────────────────────────────────────
+(er-lx-test "keytake hit value tag"
+  (er-lx-nm "element(1, lists:keytake(b, 1, [{a,1},{b,2},{c,3}]))") "value")
+
+(er-lx-test "keytake hit tuple"
+  (er-lx-nm
+    "element(2, lists:keytake(b, 1, [{a,1},{b,2},{c,3}])) =:= {b,2}") "true")
+
+(er-lx-test "keytake hit rest"
+  (er-lx-nm
+    "element(3, lists:keytake(b, 1, [{a,1},{b,2},{c,3}])) =:= [{a,1},{c,3}]") "true")
+
+(er-lx-test "keytake miss false"
+  (er-lx-nm "lists:keytake(z, 1, [{a,1}])") "false")
+
+;; ── lists:keysort/2 ───────────────────────────────────────────────
+(er-lx-test "keysort by element 1"
+  (er-lx-nm
+    "lists:keysort(1, [{c,3},{a,1},{b,2}]) =:= [{a,1},{b,2},{c,3}]") "true")
+
+(er-lx-test "keysort by element 2"
+  (er-lx-nm
+    "lists:keysort(2, [{a,3},{b,1},{c,2}]) =:= [{b,1},{c,2},{a,3}]") "true")
+
+(er-lx-test "keysort stable on equal keys"
+  (er-lx-nm
+    "lists:keysort(1, [{a,1},{a,2},{a,3}]) =:= [{a,1},{a,2},{a,3}]") "true")
+
+;; ── lists:foldr/3 ─────────────────────────────────────────────────
+(er-lx-test "foldr preserves order"
+  (er-lx-nm
+    "lists:foldr(fun(X,Acc) -> [X|Acc] end, [], [1,2,3]) =:= [1,2,3]") "true")
+
+(er-lx-test "foldr sum"
+  (erlang-eval-ast "lists:foldr(fun(X,A) -> X+A end, 0, [1,2,3,4])") 10)
+
+(er-lx-test "foldr empty returns acc"
+  (erlang-eval-ast "lists:foldr(fun(X,A) -> X+A end, 42, [])") 42)
+
+;; ── lists:partition/2 ─────────────────────────────────────────────
+(er-lx-test "partition evens/odds"
+  (er-lx-nm
+    "lists:partition(fun(X) -> X rem 2 =:= 0 end, [1,2,3,4,5]) =:= {[2,4],[1,3,5]}")
+  "true")
+
+(er-lx-test "partition all satisfy"
+  (er-lx-nm "lists:partition(fun(_) -> true end, [1,2]) =:= {[1,2],[]}") "true")
+
+(er-lx-test "partition empty"
+  (er-lx-nm "lists:partition(fun(_) -> true end, []) =:= {[],[]}") "true")
+
+;; ── lists:takewhile/2 ─────────────────────────────────────────────
+(er-lx-test "takewhile prefix"
+  (er-lx-nm "lists:takewhile(fun(X) -> X < 3 end, [1,2,3,4,1]) =:= [1,2]") "true")
+
+(er-lx-test "takewhile none"
+  (er-lx-nm "lists:takewhile(fun(X) -> X < 0 end, [1,2]) =:= []") "true")
+
+(er-lx-test "takewhile all"
+  (er-lx-nm "lists:takewhile(fun(X) -> X < 9 end, [1,2,3]) =:= [1,2,3]") "true")
+
+;; ── lists:dropwhile/2 ─────────────────────────────────────────────
+(er-lx-test "dropwhile prefix"
+  (er-lx-nm "lists:dropwhile(fun(X) -> X < 3 end, [1,2,3,4,1]) =:= [3,4,1]") "true")
+
+(er-lx-test "dropwhile all"
+  (er-lx-nm "lists:dropwhile(fun(X) -> X < 9 end, [1,2,3]) =:= []") "true")
+
+(er-lx-test "dropwhile none"
+  (er-lx-nm "lists:dropwhile(fun(X) -> X < 0 end, [1,2]) =:= [1,2]") "true")
+
+;; ── lists:splitwith/2 ─────────────────────────────────────────────
+(er-lx-test "splitwith"
+  (er-lx-nm
+    "lists:splitwith(fun(X) -> X < 3 end, [1,2,3,4,1]) =:= {[1,2],[3,4,1]}") "true")
+
+(er-lx-test "splitwith empty"
+  (er-lx-nm "lists:splitwith(fun(_) -> true end, []) =:= {[],[]}") "true")
+
+;; ── lists:flatten/1 ───────────────────────────────────────────────
+(er-lx-test "flatten nested"
+  (er-lx-nm "lists:flatten([1,[2,[3,4]],5]) =:= [1,2,3,4,5]") "true")
+
+(er-lx-test "flatten already flat"
+  (er-lx-nm "lists:flatten([1,2,3]) =:= [1,2,3]") "true")
+
+(er-lx-test "flatten empty"
+  (er-lx-nm "lists:flatten([]) =:= []") "true")
+
+(er-lx-test "flatten deep empties"
+  (er-lx-nm "lists:flatten([[],[1],[[]]]) =:= [1]") "true")
+
+(er-lx-test "flatten length"
+  (erlang-eval-ast "length(lists:flatten([[1,2],[3],[4,5,6]]))") 6)
+
+;; ── lists:max/1 ───────────────────────────────────────────────────
+(er-lx-test "max ints"
+  (erlang-eval-ast "lists:max([3,1,4,1,5,9,2,6])") 9)
+
+(er-lx-test "max single"
+  (erlang-eval-ast "lists:max([7])") 7)
+
+(er-lx-test "max atoms term order"
+  (er-lx-nm "lists:max([a,c,b]) =:= c") "true")
+
+;; ── lists:min/1 ───────────────────────────────────────────────────
+(er-lx-test "min ints"
+  (erlang-eval-ast "lists:min([3,1,4,1,5])") 1)
+
+(er-lx-test "min mixed term order"
+  (er-lx-nm "lists:min([a,1,b]) =:= 1") "true")
+
+;; ── lists:zip/2 ───────────────────────────────────────────────────
+(er-lx-test "zip pairs"
+  (er-lx-nm "lists:zip([a,b,c],[1,2,3]) =:= [{a,1},{b,2},{c,3}]") "true")
+
+(er-lx-test "zip empty"
+  (er-lx-nm "lists:zip([],[]) =:= []") "true")
+
+(er-lx-test "zip length"
+  (erlang-eval-ast "length(lists:zip([1,2],[3,4]))") 2)
+
+;; ── lists:zipwith/3 ───────────────────────────────────────────────
+(er-lx-test "zipwith sum"
+  (er-lx-nm
+    "lists:zipwith(fun(X,Y) -> X+Y end, [1,2,3], [10,20,30]) =:= [11,22,33]")
+  "true")
+
+(er-lx-test "zipwith tuple"
+  (er-lx-nm "lists:zipwith(fun(X,Y) -> {X,Y} end, [a], [1]) =:= [{a,1}]") "true")
+
+;; ── lists:unzip/1 ─────────────────────────────────────────────────
+(er-lx-test "unzip"
+  (er-lx-nm "lists:unzip([{a,1},{b,2},{c,3}]) =:= {[a,b,c],[1,2,3]}") "true")
+
+(er-lx-test "unzip empty"
+  (er-lx-nm "lists:unzip([]) =:= {[],[]}") "true")
+
+(er-lx-test "zip/unzip roundtrip"
+  (er-lx-nm "lists:unzip(lists:zip([1,2],[3,4])) =:= {[1,2],[3,4]}") "true")
+
+;; ── lists:sublist/2,3 ─────────────────────────────────────────────
+(er-lx-test "sublist/2 first n"
+  (er-lx-nm "lists:sublist([1,2,3,4,5],3) =:= [1,2,3]") "true")
+
+(er-lx-test "sublist/2 over length"
+  (er-lx-nm "lists:sublist([1,2],5) =:= [1,2]") "true")
+
+(er-lx-test "sublist/2 zero"
+  (er-lx-nm "lists:sublist([1,2,3],0) =:= []") "true")
+
+(er-lx-test "sublist/3 mid"
+  (er-lx-nm "lists:sublist([1,2,3,4,5],2,3) =:= [2,3,4]") "true")
+
+(er-lx-test "sublist/3 to end"
+  (er-lx-nm "lists:sublist([1,2,3],2,10) =:= [2,3]") "true")
+
+;; ── lists:nthtail/2 ───────────────────────────────────────────────
+(er-lx-test "nthtail mid"
+  (er-lx-nm "lists:nthtail(2,[1,2,3,4]) =:= [3,4]") "true")
+
+(er-lx-test "nthtail zero"
+  (er-lx-nm "lists:nthtail(0,[1,2]) =:= [1,2]") "true")
+
+(er-lx-test "nthtail full"
+  (er-lx-nm "lists:nthtail(3,[1,2,3]) =:= []") "true")
+
+;; ── lists:split/2 ─────────────────────────────────────────────────
+(er-lx-test "split mid"
+  (er-lx-nm "lists:split(2,[1,2,3,4,5]) =:= {[1,2],[3,4,5]}") "true")
+
+(er-lx-test "split zero"
+  (er-lx-nm "lists:split(0,[1,2]) =:= {[],[1,2]}") "true")
+
+(er-lx-test "split full"
+  (er-lx-nm "lists:split(3,[1,2,3]) =:= {[1,2,3],[]}") "true")
+
+;; ── lists:droplast/1 ──────────────────────────────────────────────
+(er-lx-test "droplast"
+  (er-lx-nm "lists:droplast([1,2,3]) =:= [1,2]") "true")
+
+(er-lx-test "droplast single"
+  (er-lx-nm "lists:droplast([9]) =:= []") "true")
+
+;; ── lists:flatmap/2 ───────────────────────────────────────────────
+(er-lx-test "flatmap duplicates"
+  (er-lx-nm "lists:flatmap(fun(X) -> [X,X] end, [1,2]) =:= [1,1,2,2]") "true")
+
+(er-lx-test "flatmap empty"
+  (er-lx-nm "lists:flatmap(fun(X) -> [X] end, []) =:= []") "true")
+
+;; ── lists:filtermap/2 ─────────────────────────────────────────────
+(er-lx-test "filtermap transform"
+  (er-lx-nm
+    "lists:filtermap(fun(X) -> case X rem 2 of 0 -> {true, X*10}; _ -> false end end, [1,2,3,4]) =:= [20,40]")
+  "true")
+
+(er-lx-test "filtermap bool keep"
+  (er-lx-nm "lists:filtermap(fun(X) -> X > 2 end, [1,2,3,4]) =:= [3,4]") "true")
+
+;; ── lists:mapfoldl/3 ──────────────────────────────────────────────
+(er-lx-test "mapfoldl map+acc"
+  (er-lx-nm
+    "lists:mapfoldl(fun(X,A) -> {X*2, A+X} end, 0, [1,2,3]) =:= {[2,4,6],6}") "true")
+
+(er-lx-test "mapfoldl empty"
+  (er-lx-nm "lists:mapfoldl(fun(X,A) -> {X,A} end, 5, []) =:= {[],5}") "true")
+
+;; ── lists:search/2 ────────────────────────────────────────────────
+(er-lx-test "search hit"
+  (er-lx-nm "lists:search(fun(X) -> X > 2 end, [1,2,3,4]) =:= {value,3}") "true")
+
+(er-lx-test "search miss"
+  (er-lx-nm "lists:search(fun(X) -> X > 9 end, [1,2,3])") "false")
+
+;; ── proplists:get_value/2,3 ───────────────────────────────────────
+(er-lx-test "pl get_value hit"
+  (erlang-eval-ast "proplists:get_value(b, [{a,1},{b,2}])") 2)
+
+(er-lx-test "pl get_value miss undefined"
+  (er-lx-nm "proplists:get_value(z, [{a,1}])") "undefined")
+
+(er-lx-test "pl get_value default"
+  (erlang-eval-ast "proplists:get_value(z, [{a,1}], 99)") 99)
+
+(er-lx-test "pl get_value bare atom is true"
+  (er-lx-nm "proplists:get_value(flag, [flag, {a,1}])") "true")
+
+(er-lx-test "pl get_value first occurrence"
+  (erlang-eval-ast "proplists:get_value(a, [{a,1},{a,2}])") 1)
+
+;; ── proplists:get_all_values/2 ────────────────────────────────────
+(er-lx-test "pl get_all_values"
+  (er-lx-nm
+    "proplists:get_all_values(a, [{a,1},{b,2},{a,3}]) =:= [1,3]") "true")
+
+;; ── proplists:is_defined/2 ────────────────────────────────────────
+(er-lx-test "pl is_defined true"
+  (er-lx-nm "proplists:is_defined(b, [{a,1},{b,2}])") "true")
+
+(er-lx-test "pl is_defined false"
+  (er-lx-nm "proplists:is_defined(z, [{a,1}])") "false")
+
+;; ── proplists:lookup/2 ────────────────────────────────────────────
+(er-lx-test "pl lookup hit"
+  (er-lx-nm "proplists:lookup(b, [{a,1},{b,2}]) =:= {b,2}") "true")
+
+(er-lx-test "pl lookup bare atom"
+  (er-lx-nm "proplists:lookup(flag, [flag]) =:= {flag,true}") "true")
+
+(er-lx-test "pl lookup miss"
+  (er-lx-nm "proplists:lookup(z, [{a,1}])") "none")
+
+;; ── proplists:delete/2 ────────────────────────────────────────────
+(er-lx-test "pl delete removes all"
+  (er-lx-nm "proplists:delete(a, [{a,1},{b,2},{a,3}]) =:= [{b,2}]") "true")
diff --git a/lib/erlang/transpile.sx b/lib/erlang/transpile.sx
index 6ed64b87..cc8dc057 100644
--- a/lib/erlang/transpile.sx
+++ b/lib/erlang/transpile.sx
@@ -2045,4 +2045,657 @@
         (range 0 (len ks)))
       out)))
 
+;; ── extra lists + proplists BIFs (folded from loops/erlang lists-ext) ──
+;; ── cons <-> SX-list bridges ──────────────────────────────────────
+(define
+  er-cons->sxlist
+  (fn (lst)
+    (cond
+      (er-nil? lst) (list)
+      (er-cons? lst) (cons (get lst :head) (er-cons->sxlist (get lst :tail)))
+      :else (raise (er-mk-error-marker (er-mk-atom "badarg"))))))
 
+(define
+  er-sxlist->cons
+  (fn (xs)
+    (if (= (len xs) 0)
+      (er-mk-nil)
+      (er-mk-cons (first xs) (er-sxlist->cons (rest xs))))))
+
+;; ── merge sort over SX lists (stable) ─────────────────────────────
+(define
+  er-ext-take
+  (fn (xs n)
+    (if (or (= n 0) (= (len xs) 0))
+      (list)
+      (cons (first xs) (er-ext-take (rest xs) (- n 1))))))
+
+(define
+  er-ext-drop
+  (fn (xs n)
+    (if (or (= n 0) (= (len xs) 0))
+      xs
+      (er-ext-drop (rest xs) (- n 1)))))
+
+;; le? returns a truthy value (Erlang bool atom or SX bool) iff a
+;; should sort at-or-before b. Taking from the left half first on a
+;; true result keeps the sort stable.
+(define
+  er-ext-merge
+  (fn (a b le?)
+    (cond
+      (= (len a) 0) b
+      (= (len b) 0) a
+      (er-truthy? (le? (first a) (first b)))
+        (cons (first a) (er-ext-merge (rest a) b le?))
+      :else (cons (first b) (er-ext-merge a (rest b) le?)))))
+
+(define
+  er-ext-msort
+  (fn (xs le?)
+    (if (<= (len xs) 1)
+      xs
+      (let ((mid (quotient (len xs) 2)))
+        (er-ext-merge
+          (er-ext-msort (er-ext-take xs mid) le?)
+          (er-ext-msort (er-ext-drop xs mid) le?)
+          le?)))))
+
+;; Full Erlang term order. The shared er-lt? (transpile.sx) only
+;; deep-compares numbers/atoms/strings and otherwise falls back to a
+;; coarse type rank — so any two tuples (or two lists) compare as
+;; order-equal there. er-ext-lt? adds the missing structural cases:
+;; tuples by arity then elementwise, lists elementwise with a shorter
+;; proper prefix sorting first. Cross-type cases delegate to er-lt?.
+(define
+  er-ext-lt-seq
+  (fn (ea eb i)
+    (cond
+      (>= i (len ea)) false
+      (er-ext-lt? (nth ea i) (nth eb i)) true
+      (er-ext-lt? (nth eb i) (nth ea i)) false
+      :else (er-ext-lt-seq ea eb (+ i 1)))))
+
+(define
+  er-ext-lt?
+  (fn (a b)
+    (cond
+      (and (er-tuple? a) (er-tuple? b))
+        (let ((ea (get a :elements)) (eb (get b :elements)))
+          (cond
+            (< (len ea) (len eb)) true
+            (> (len ea) (len eb)) false
+            :else (er-ext-lt-seq ea eb 0)))
+      (and (er-cons? a) (er-cons? b))
+        (cond
+          (er-ext-lt? (get a :head) (get b :head)) true
+          (er-ext-lt? (get b :head) (get a :head)) false
+          :else (er-ext-lt? (get a :tail) (get b :tail)))
+      (and (er-nil? a) (er-cons? b)) true
+      (and (er-cons? a) (er-nil? b)) false
+      (and (er-nil? a) (er-nil? b)) false
+      :else (er-lt? a b))))
+
+;; Default Erlang term order: a =< b  ==  not (b < a).
+(define
+  er-ext-term-le
+  (fn (a b) (er-bool (not (er-ext-lt? b a)))))
+
+;; ── lists:sort/1, lists:sort/2 ────────────────────────────────────
+(define
+  er-bif-lists-sort
+  (fn (vs)
+    (cond
+      (= (len vs) 1)
+        (er-sxlist->cons
+          (er-ext-msort (er-cons->sxlist (nth vs 0)) er-ext-term-le))
+      (= (len vs) 2)
+        (let ((f (nth vs 0)) (lst (nth vs 1)))
+          (er-sxlist->cons
+            (er-ext-msort
+              (er-cons->sxlist lst)
+              (fn (a b) (er-apply-fun f (list a b))))))
+      :else (error "Erlang: lists:sort: wrong arity"))))
+
+;; ── lists:usort/1 (sort then drop adjacent term-equal dups) ───────
+(define
+  er-ext-dedup
+  (fn (xs)
+    (cond
+      (= (len xs) 0) (list)
+      (= (len xs) 1) xs
+      (er-equal? (first xs) (nth xs 1)) (er-ext-dedup (rest xs))
+      :else (cons (first xs) (er-ext-dedup (rest xs))))))
+
+(define
+  er-bif-lists-usort
+  (fn (vs)
+    (let ((lst (er-bif-arg1 vs "lists:usort")))
+      (er-sxlist->cons
+        (er-ext-dedup
+          (er-ext-msort (er-cons->sxlist lst) er-ext-term-le))))))
+
+;; ── keylists (lists of tuples keyed on element N, 1-indexed) ──────
+;; keyfind/keymember/keydelete/keyreplace/keystore/keytake/keysort.
+;; Key comparison is == (er-equal?), matching the standard lib. Only
+;; the FIRST matching tuple is acted on. Non-tuples / tuples shorter
+;; than N never match and are passed through unchanged.
+(define
+  er-ext-tup-elem
+  (fn (tup n)
+    (if (er-tuple? tup)
+      (let ((es (get tup :elements)))
+        (if (and (>= n 1) (<= n (len es))) (nth es (- n 1)) nil))
+      nil)))
+
+(define
+  er-ext-key-match?
+  (fn (key n tup)
+    (and
+      (er-tuple? tup)
+      (>= n 1)
+      (<= n (len (get tup :elements)))
+      (er-equal? key (nth (get tup :elements) (- n 1))))))
+
+(define
+  er-ext-keyfind
+  (fn (key n lst)
+    (cond
+      (er-nil? lst) (er-mk-atom "false")
+      (er-cons? lst)
+        (if (er-ext-key-match? key n (get lst :head))
+          (get lst :head)
+          (er-ext-keyfind key n (get lst :tail)))
+      :else (er-mk-atom "false"))))
+
+(define
+  er-ext-keydelete
+  (fn (key n lst)
+    (cond
+      (er-nil? lst) (er-mk-nil)
+      (er-cons? lst)
+        (if (er-ext-key-match? key n (get lst :head))
+          (get lst :tail)
+          (er-mk-cons (get lst :head) (er-ext-keydelete key n (get lst :tail))))
+      :else lst)))
+
+(define
+  er-ext-keyreplace
+  (fn (key n lst new)
+    (cond
+      (er-nil? lst) (er-mk-nil)
+      (er-cons? lst)
+        (if (er-ext-key-match? key n (get lst :head))
+          (er-mk-cons new (get lst :tail))
+          (er-mk-cons (get lst :head) (er-ext-keyreplace key n (get lst :tail) new)))
+      :else lst)))
+
+(define
+  er-ext-keystore
+  (fn (key n lst new)
+    (cond
+      (er-nil? lst) (er-mk-cons new (er-mk-nil))
+      (er-cons? lst)
+        (if (er-ext-key-match? key n (get lst :head))
+          (er-mk-cons new (get lst :tail))
+          (er-mk-cons (get lst :head) (er-ext-keystore key n (get lst :tail) new)))
+      :else lst)))
+
+(define
+  er-bif-lists-keyfind
+  (fn (vs) (er-ext-keyfind (nth vs 0) (nth vs 1) (nth vs 2))))
+
+(define
+  er-bif-lists-keymember
+  (fn (vs)
+    (er-bool (not (er-atom? (er-ext-keyfind (nth vs 0) (nth vs 1) (nth vs 2)))))))
+
+(define
+  er-bif-lists-keydelete
+  (fn (vs) (er-ext-keydelete (nth vs 0) (nth vs 1) (nth vs 2))))
+
+(define
+  er-bif-lists-keyreplace
+  (fn (vs) (er-ext-keyreplace (nth vs 0) (nth vs 1) (nth vs 2) (nth vs 3))))
+
+(define
+  er-bif-lists-keystore
+  (fn (vs) (er-ext-keystore (nth vs 0) (nth vs 1) (nth vs 2) (nth vs 3))))
+
+(define
+  er-bif-lists-keytake
+  (fn (vs)
+    (let ((key (nth vs 0)) (n (nth vs 1)) (lst (nth vs 2)))
+      (let ((hit (er-ext-keyfind key n lst)))
+        (if (er-atom? hit)
+          (er-mk-atom "false")
+          (er-mk-tuple
+            (list (er-mk-atom "value") hit (er-ext-keydelete key n lst))))))))
+
+(define
+  er-bif-lists-keysort
+  (fn (vs)
+    (let ((n (nth vs 0)) (lst (nth vs 1)))
+      (er-sxlist->cons
+        (er-ext-msort
+          (er-cons->sxlist lst)
+          (fn (a b)
+            (er-bool
+              (not (er-ext-lt? (er-ext-tup-elem b n) (er-ext-tup-elem a n))))))))))
+
+;; ── higher-order traversal (foldr / partition / *while) ───────────
+(define
+  er-ext-foldr
+  (fn (f acc lst)
+    (cond
+      (er-nil? lst) acc
+      (er-cons? lst)
+        (er-apply-fun f (list (get lst :head) (er-ext-foldr f acc (get lst :tail))))
+      :else (raise (er-mk-error-marker (er-mk-atom "badarg"))))))
+
+(define
+  er-bif-lists-foldr
+  (fn (vs) (er-ext-foldr (nth vs 0) (nth vs 1) (nth vs 2))))
+
+(define
+  er-ext-partition
+  (fn (pred lst yes no)
+    (cond
+      (er-nil? lst)
+        (er-mk-tuple
+          (list
+            (er-list-reverse-iter yes (er-mk-nil))
+            (er-list-reverse-iter no (er-mk-nil))))
+      (er-cons? lst)
+        (if (er-truthy? (er-apply-fun pred (list (get lst :head))))
+          (er-ext-partition pred (get lst :tail) (er-mk-cons (get lst :head) yes) no)
+          (er-ext-partition pred (get lst :tail) yes (er-mk-cons (get lst :head) no)))
+      :else (raise (er-mk-error-marker (er-mk-atom "badarg"))))))
+
+(define
+  er-bif-lists-partition
+  (fn (vs) (er-ext-partition (nth vs 0) (nth vs 1) (er-mk-nil) (er-mk-nil))))
+
+(define
+  er-ext-takewhile
+  (fn (pred lst)
+    (cond
+      (er-nil? lst) (er-mk-nil)
+      (er-cons? lst)
+        (if (er-truthy? (er-apply-fun pred (list (get lst :head))))
+          (er-mk-cons (get lst :head) (er-ext-takewhile pred (get lst :tail)))
+          (er-mk-nil))
+      :else (er-mk-nil))))
+
+(define
+  er-bif-lists-takewhile
+  (fn (vs) (er-ext-takewhile (nth vs 0) (nth vs 1))))
+
+(define
+  er-ext-dropwhile
+  (fn (pred lst)
+    (cond
+      (er-nil? lst) (er-mk-nil)
+      (er-cons? lst)
+        (if (er-truthy? (er-apply-fun pred (list (get lst :head))))
+          (er-ext-dropwhile pred (get lst :tail))
+          lst)
+      :else lst)))
+
+(define
+  er-bif-lists-dropwhile
+  (fn (vs) (er-ext-dropwhile (nth vs 0) (nth vs 1))))
+
+(define
+  er-bif-lists-splitwith
+  (fn (vs)
+    (let ((pred (nth vs 0)) (lst (nth vs 1)))
+      (er-mk-tuple
+        (list (er-ext-takewhile pred lst) (er-ext-dropwhile pred lst))))))
+
+;; ── structural / aggregate (flatten / max / min) ──────────────────
+(define
+  er-ext-flatten
+  (fn (lst)
+    (cond
+      (er-nil? lst) (er-mk-nil)
+      (er-cons? lst)
+        (let ((h (get lst :head)))
+          (if (or (er-nil? h) (er-cons? h))
+            (er-list-append (er-ext-flatten h) (er-ext-flatten (get lst :tail)))
+            (er-mk-cons h (er-ext-flatten (get lst :tail)))))
+      :else (raise (er-mk-error-marker (er-mk-atom "badarg"))))))
+
+(define
+  er-bif-lists-flatten
+  (fn (vs) (er-ext-flatten (er-bif-arg1 vs "lists:flatten"))))
+
+(define
+  er-ext-extreme
+  (fn (lst best lt?)
+    (cond
+      (er-nil? lst) best
+      (er-cons? lst)
+        (er-ext-extreme
+          (get lst :tail)
+          (if (lt? best (get lst :head)) (get lst :head) best)
+          lt?)
+      :else best)))
+
+(define
+  er-bif-lists-max
+  (fn (vs)
+    (let ((lst (er-bif-arg1 vs "lists:max")))
+      (if (er-cons? lst)
+        (er-ext-extreme (get lst :tail) (get lst :head)
+          (fn (a b) (er-ext-lt? a b)))
+        (raise (er-mk-error-marker (er-mk-atom "badarg")))))))
+
+(define
+  er-bif-lists-min
+  (fn (vs)
+    (let ((lst (er-bif-arg1 vs "lists:min")))
+      (if (er-cons? lst)
+        (er-ext-extreme (get lst :tail) (get lst :head)
+          (fn (a b) (er-ext-lt? b a)))
+        (raise (er-mk-error-marker (er-mk-atom "badarg")))))))
+
+;; ── zip family (zip / zipwith / unzip) ────────────────────────────
+;; Length mismatch raises badarg (real Erlang raises function_clause;
+;; badarg is the closest in-port equivalent).
+(define
+  er-ext-zip
+  (fn (a b)
+    (cond
+      (and (er-nil? a) (er-nil? b)) (er-mk-nil)
+      (and (er-cons? a) (er-cons? b))
+        (er-mk-cons
+          (er-mk-tuple (list (get a :head) (get b :head)))
+          (er-ext-zip (get a :tail) (get b :tail)))
+      :else (raise (er-mk-error-marker (er-mk-atom "badarg"))))))
+
+(define
+  er-bif-lists-zip
+  (fn (vs) (er-ext-zip (nth vs 0) (nth vs 1))))
+
+(define
+  er-ext-zipwith
+  (fn (f a b)
+    (cond
+      (and (er-nil? a) (er-nil? b)) (er-mk-nil)
+      (and (er-cons? a) (er-cons? b))
+        (er-mk-cons
+          (er-apply-fun f (list (get a :head) (get b :head)))
+          (er-ext-zipwith f (get a :tail) (get b :tail)))
+      :else (raise (er-mk-error-marker (er-mk-atom "badarg"))))))
+
+(define
+  er-bif-lists-zipwith
+  (fn (vs) (er-ext-zipwith (nth vs 0) (nth vs 1) (nth vs 2))))
+
+(define
+  er-ext-unzip
+  (fn (lst as bs)
+    (cond
+      (er-nil? lst)
+        (er-mk-tuple
+          (list
+            (er-list-reverse-iter as (er-mk-nil))
+            (er-list-reverse-iter bs (er-mk-nil))))
+      (and (er-cons? lst) (er-tuple? (get lst :head)))
+        (let ((es (get (get lst :head) :elements)))
+          (if (= (len es) 2)
+            (er-ext-unzip (get lst :tail)
+              (er-mk-cons (nth es 0) as)
+              (er-mk-cons (nth es 1) bs))
+            (raise (er-mk-error-marker (er-mk-atom "badarg")))))
+      :else (raise (er-mk-error-marker (er-mk-atom "badarg"))))))
+
+(define
+  er-bif-lists-unzip
+  (fn (vs)
+    (er-ext-unzip (er-bif-arg1 vs "lists:unzip") (er-mk-nil) (er-mk-nil))))
+
+;; ── slicing (sublist / nthtail / split / droplast) ────────────────
+(define
+  er-ext-sublist2
+  (fn (lst n)
+    (cond
+      (or (<= n 0) (er-nil? lst)) (er-mk-nil)
+      (er-cons? lst)
+        (er-mk-cons (get lst :head) (er-ext-sublist2 (get lst :tail) (- n 1)))
+      :else (er-mk-nil))))
+
+;; lenient drop (used by sublist/3); never raises
+(define
+  er-ext-drop-cons
+  (fn (lst n)
+    (cond
+      (or (<= n 0) (er-nil? lst)) lst
+      (er-cons? lst) (er-ext-drop-cons (get lst :tail) (- n 1))
+      :else lst)))
+
+;; strict drop (used by nthtail/2 + split/2); raises if list too short
+(define
+  er-ext-nthtail
+  (fn (n lst)
+    (cond
+      (<= n 0) lst
+      (er-cons? lst) (er-ext-nthtail (- n 1) (get lst :tail))
+      :else (raise (er-mk-error-marker (er-mk-atom "badarg"))))))
+
+(define
+  er-bif-lists-sublist
+  (fn (vs)
+    (cond
+      (= (len vs) 2) (er-ext-sublist2 (nth vs 0) (nth vs 1))
+      (= (len vs) 3)
+        (er-ext-sublist2
+          (er-ext-drop-cons (nth vs 0) (- (nth vs 1) 1))
+          (nth vs 2))
+      :else (error "Erlang: lists:sublist: wrong arity"))))
+
+(define
+  er-bif-lists-nthtail
+  (fn (vs) (er-ext-nthtail (nth vs 0) (nth vs 1))))
+
+(define
+  er-bif-lists-split
+  (fn (vs)
+    (let ((n (nth vs 0)) (lst (nth vs 1)))
+      (er-mk-tuple
+        (list (er-ext-sublist2 lst n) (er-ext-nthtail n lst))))))
+
+(define
+  er-ext-droplast
+  (fn (lst)
+    (cond
+      (and (er-cons? lst) (er-nil? (get lst :tail))) (er-mk-nil)
+      (er-cons? lst) (er-mk-cons (get lst :head) (er-ext-droplast (get lst :tail)))
+      :else (raise (er-mk-error-marker (er-mk-atom "badarg"))))))
+
+(define
+  er-bif-lists-droplast
+  (fn (vs) (er-ext-droplast (er-bif-arg1 vs "lists:droplast"))))
+
+;; ── more higher-order (flatmap / filtermap / mapfoldl / search) ───
+(define
+  er-ext-flatmap
+  (fn (f lst)
+    (cond
+      (er-nil? lst) (er-mk-nil)
+      (er-cons? lst)
+        (er-list-append
+          (er-apply-fun f (list (get lst :head)))
+          (er-ext-flatmap f (get lst :tail)))
+      :else (raise (er-mk-error-marker (er-mk-atom "badarg"))))))
+
+(define
+  er-bif-lists-flatmap
+  (fn (vs) (er-ext-flatmap (nth vs 0) (nth vs 1))))
+
+(define
+  er-ext-atom-true?
+  (fn (v) (and (er-atom? v) (= (get v :name) "true"))))
+
+(define
+  er-ext-filtermap
+  (fn (f lst)
+    (cond
+      (er-nil? lst) (er-mk-nil)
+      (er-cons? lst)
+        (let ((r (er-apply-fun f (list (get lst :head)))))
+          (cond
+            (er-ext-atom-true? r)
+              (er-mk-cons (get lst :head) (er-ext-filtermap f (get lst :tail)))
+            (and
+              (er-tuple? r)
+              (= (len (get r :elements)) 2)
+              (er-ext-atom-true? (nth (get r :elements) 0)))
+              (er-mk-cons (nth (get r :elements) 1) (er-ext-filtermap f (get lst :tail)))
+            :else (er-ext-filtermap f (get lst :tail))))
+      :else (raise (er-mk-error-marker (er-mk-atom "badarg"))))))
+
+(define
+  er-bif-lists-filtermap
+  (fn (vs) (er-ext-filtermap (nth vs 0) (nth vs 1))))
+
+(define
+  er-ext-mapfoldl
+  (fn (f acc lst mapped)
+    (cond
+      (er-nil? lst)
+        (er-mk-tuple (list (er-list-reverse-iter mapped (er-mk-nil)) acc))
+      (er-cons? lst)
+        (let ((r (er-apply-fun f (list (get lst :head) acc))))
+          (let ((es (get r :elements)))
+            (er-ext-mapfoldl f (nth es 1) (get lst :tail)
+              (er-mk-cons (nth es 0) mapped))))
+      :else (raise (er-mk-error-marker (er-mk-atom "badarg"))))))
+
+(define
+  er-bif-lists-mapfoldl
+  (fn (vs) (er-ext-mapfoldl (nth vs 0) (nth vs 1) (nth vs 2) (er-mk-nil))))
+
+(define
+  er-ext-search
+  (fn (pred lst)
+    (cond
+      (er-nil? lst) (er-mk-atom "false")
+      (er-cons? lst)
+        (if (er-truthy? (er-apply-fun pred (list (get lst :head))))
+          (er-mk-tuple (list (er-mk-atom "value") (get lst :head)))
+          (er-ext-search pred (get lst :tail)))
+      :else (er-mk-atom "false"))))
+
+(define
+  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))))