diff --git a/antlr-parser/src/main/antlr4/com/compilerprogramming/ezlang/antlr/EZLanguage.g4 b/antlr-parser/src/main/antlr4/com/compilerprogramming/ezlang/antlr/EZLanguage.g4
index cb06926..57fe47c 100644
--- a/antlr-parser/src/main/antlr4/com/compilerprogramming/ezlang/antlr/EZLanguage.g4
+++ b/antlr-parser/src/main/antlr4/com/compilerprogramming/ezlang/antlr/EZLanguage.g4
@@ -91,7 +91,7 @@ multiplicationExpression
     ;
 
 unaryExpression
-    : ('-' | '!') unaryExpression
+    : ('-' | '!' | '#') unaryExpression
     | postfixExpression
     ;
 
@@ -183,4 +183,4 @@ LINE_COMMENT
     ;
 
 
-ANY: . ;
\ No newline at end of file
+ANY: . ;
diff --git a/docs/ez-lang.rst b/docs/ez-lang.rst
index 46e0756..9099ae6 100644
--- a/docs/ez-lang.rst
+++ b/docs/ez-lang.rst
@@ -222,6 +222,7 @@ Following table describes the available operators by their precedence (low to hi
 | ``%``      |                 |          |
 +------------+-----------------+----------+
 | ``-``      | negate          | Unary    |
+| ``#``      | array length    | Unary    |
 | ``!``      |                 |          |
 +------------+-----------------+----------+
 | ``(...)``, | function call,  | Postfix  |
diff --git a/lexer/src/main/java/com/compilerprogramming/ezlang/lexer/Lexer.java b/lexer/src/main/java/com/compilerprogramming/ezlang/lexer/Lexer.java
index 295c7e1..d673446 100644
--- a/lexer/src/main/java/com/compilerprogramming/ezlang/lexer/Lexer.java
+++ b/lexer/src/main/java/com/compilerprogramming/ezlang/lexer/Lexer.java
@@ -154,6 +154,7 @@ public Token scan() {
                 case ',':
                 case '.':
                 case '%':
+                case '#':
                 case '+':
                 case '*':
                 case ';':
diff --git a/lexer/src/test/java/com/compilerprogramming/ezlang/lexer/TestLexer.java b/lexer/src/test/java/com/compilerprogramming/ezlang/lexer/TestLexer.java
index 32d1614..49bd2d8 100644
--- a/lexer/src/test/java/com/compilerprogramming/ezlang/lexer/TestLexer.java
+++ b/lexer/src/test/java/com/compilerprogramming/ezlang/lexer/TestLexer.java
@@ -12,7 +12,7 @@ public class TestLexer {
     public void testLexer() {
         String src = """
                 // A comment
-                Ident=,>=<>>=!=!1.5{0}11()[]+-*/ //Another comment
+                Ident=,>=<>>=!=!1.5{0}11()[]+-*/# //Another comment
                 """;
         Lexer lexer = new Lexer(src);
         Token[] expected = new Token[]{
@@ -37,7 +37,8 @@ public void testLexer() {
                 Token.newPunct("+", 0),
                 Token.newPunct("-", 0),
                 Token.newPunct("*", 0),
-                Token.newPunct("/", 0)
+                Token.newPunct("/", 0),
+                Token.newPunct("#", 0)
         };
 
         List<Token> tokens = new ArrayList<>();
diff --git a/optvm/src/main/java/com/compilerprogramming/ezlang/compiler/SparseConditionalConstantPropagation.java b/optvm/src/main/java/com/compilerprogramming/ezlang/compiler/SparseConditionalConstantPropagation.java
index 14e1829..2992d17 100644
--- a/optvm/src/main/java/com/compilerprogramming/ezlang/compiler/SparseConditionalConstantPropagation.java
+++ b/optvm/src/main/java/com/compilerprogramming/ezlang/compiler/SparseConditionalConstantPropagation.java
@@ -452,6 +452,11 @@ private static EZType operandType(Operand operand) {
     }
 
     private static boolean evalUnary(LatticeElement cell, LatticeElement input, String unOp, EZType resultType) {
+        if (unOp.equals("#")) {
+            if (input.kind == F_TOP || input.kind == F_REF_TOP)
+                return false;
+            return cell.meetWithTypeBottom(resultType);
+        }
         if (input.isIntegerConstant()) {
             long value = input.kind == F_INT_ZERO ? 0 : input.intValue;
             if (unOp.equals("-"))
diff --git a/optvm/src/main/java/com/compilerprogramming/ezlang/interpreter/Interpreter.java b/optvm/src/main/java/com/compilerprogramming/ezlang/interpreter/Interpreter.java
index a32834b..4798ddf 100644
--- a/optvm/src/main/java/com/compilerprogramming/ezlang/interpreter/Interpreter.java
+++ b/optvm/src/main/java/com/compilerprogramming/ezlang/interpreter/Interpreter.java
@@ -153,6 +153,9 @@ else if (arg instanceof Operand.NullConstantOperand) {
                     else if (unaryValue instanceof Value.FloatValue floatValue && unaryInst.unop.equals("-")) {
                         execStack.stack[base + unaryInst.result().frameSlot()] = new Value.FloatValue(-floatValue.value);
                     }
+                    else if (unaryValue instanceof Value.ArrayValue arrayValue && unaryInst.unop.equals("#")) {
+                        execStack.stack[base + unaryInst.result().frameSlot()] = new Value.IntegerValue(arrayValue.values.size());
+                    }
                     else
                         throw new IllegalStateException("Unexpected unary operand: " + unaryOperand);
                 }
diff --git a/optvm/src/test/java/com/compilerprogramming/ezlang/interpreter/TestInterpreter.java b/optvm/src/test/java/com/compilerprogramming/ezlang/interpreter/TestInterpreter.java
index 26d3174..7ffb987 100644
--- a/optvm/src/test/java/com/compilerprogramming/ezlang/interpreter/TestInterpreter.java
+++ b/optvm/src/test/java/com/compilerprogramming/ezlang/interpreter/TestInterpreter.java
@@ -1031,4 +1031,18 @@ func main()->Int
                 integerValue.value == 1);
     }
 
+    @Test
+    public void testArrayLengthUnaryOperator() {
+        String src = """
+                func foo()->Int {
+                    var a = new [Int] {1,2,3,4}
+                    var b = new [Int] {len=0,value=0}
+                    return #a + #b
+                }
+                """;
+        var value = compileAndRun(src, "foo");
+        Assert.assertNotNull(value);
+        Assert.assertTrue(value instanceof Value.IntegerValue integerValue
+                && integerValue.value == 4);
+    }
 }
diff --git a/parser/src/main/java/com/compilerprogramming/ezlang/parser/Parser.java b/parser/src/main/java/com/compilerprogramming/ezlang/parser/Parser.java
index d185a4a..b4b60ac 100644
--- a/parser/src/main/java/com/compilerprogramming/ezlang/parser/Parser.java
+++ b/parser/src/main/java/com/compilerprogramming/ezlang/parser/Parser.java
@@ -329,7 +329,8 @@ private AST.Expr parseMultiplication(Lexer lexer) {
 
     private AST.Expr parseUnary(Lexer lexer) {
         if (isToken(currentToken, "-")
-                || isToken(currentToken, "!")) {
+                || isToken(currentToken, "!")
+                || isToken(currentToken, "#")) {
             var tok = currentToken;
             nextToken(lexer);
             return new AST.UnaryExpr(tok, parseUnary(lexer), tok.lineNumber);
diff --git a/registervm/src/main/java/com/compilerprogramming/ezlang/interpreter/Interpreter.java b/registervm/src/main/java/com/compilerprogramming/ezlang/interpreter/Interpreter.java
index 6faeace..518c84a 100644
--- a/registervm/src/main/java/com/compilerprogramming/ezlang/interpreter/Interpreter.java
+++ b/registervm/src/main/java/com/compilerprogramming/ezlang/interpreter/Interpreter.java
@@ -152,6 +152,9 @@ else if (arg instanceof Operand.NullConstantOperand) {
                     else if (unaryValue instanceof Value.FloatValue floatValue && unaryInst.unop.equals("-")) {
                         execStack.stack[base + unaryInst.result().frameSlot()] = new Value.FloatValue(-floatValue.value);
                     }
+                    else if (unaryValue instanceof Value.ArrayValue arrayValue && unaryInst.unop.equals("#")) {
+                        execStack.stack[base + unaryInst.result().frameSlot()] = new Value.IntegerValue(arrayValue.values.size());
+                    }
                     else
                         throw new IllegalStateException("Unexpected unary operand: " + unaryOperand);
                 }
diff --git a/registervm/src/test/java/com/compilerprogramming/ezlang/interpreter/TestInterpreter.java b/registervm/src/test/java/com/compilerprogramming/ezlang/interpreter/TestInterpreter.java
index ac15361..cdfedf1 100644
--- a/registervm/src/test/java/com/compilerprogramming/ezlang/interpreter/TestInterpreter.java
+++ b/registervm/src/test/java/com/compilerprogramming/ezlang/interpreter/TestInterpreter.java
@@ -558,4 +558,18 @@ func foo()->Float {
         Assert.assertTrue(value instanceof Value.FloatValue floatValue
                 && Math.abs(floatValue.value - 3.5) < 0.000001);
     }
+    @Test
+    public void testArrayLengthUnaryOperator() {
+        String src = """
+                func foo()->Int {
+                    var a = new [Int] {1,2,3}
+                    var b = new [Int] {len=0,value=0}
+                    return #a + #b
+                }
+                """;
+        var value = compileAndRun(src, "foo");
+        Assert.assertNotNull(value);
+        Assert.assertTrue(value instanceof Value.IntegerValue integerValue
+                && integerValue.value == 3);
+    }
 }
diff --git a/seaofnodes/src/main/java/com/compilerprogramming/ezlang/compiler/Compiler.java b/seaofnodes/src/main/java/com/compilerprogramming/ezlang/compiler/Compiler.java
index 6051d08..0f5b827 100644
--- a/seaofnodes/src/main/java/com/compilerprogramming/ezlang/compiler/Compiler.java
+++ b/seaofnodes/src/main/java/com/compilerprogramming/ezlang/compiler/Compiler.java
@@ -465,6 +465,25 @@ private Node compileSetFieldExpr(AST.SetFieldExpr setFieldExpr) {
         return objPtr;
     }
 
+    // # operator
+    private Node compileArrayLengthExpr(AST.Expr arrayExpr, int lineNumber) {
+        Node objPtr = compileExpr(arrayExpr).keep();
+        if( !(objPtr._type instanceof TypeMemPtr ptr) ) {
+            throw new CompilerException("Unexpected type " + objPtr._type.str(), lineNumber);
+        }
+        String name = "#";
+        TypeStruct base = ptr._obj;
+        int fidx = base.find(name);
+        if( fidx == -1 ) throw error("Accessing unknown field '" + name + "' from '" + ptr.str() + "'", lineNumber);
+        Field f = base._fields[fidx];
+        Node off = con(base.offset(fidx)).keep();
+        Node load = new LoadNode(name, f._alias, f._type, memAlias(f._alias), objPtr, off);
+        load = peep(load);
+        objPtr.unkeep();
+        off.unkeep();
+        return load;
+    }
+
     private Node compileArrayIndexExpr(AST.ArrayLoadExpr arrayLoadExpr) {
         Node objPtr = compileExpr(arrayLoadExpr.array).keep();
         // Sanity check expr for being a reference
@@ -531,12 +550,23 @@ private Node compileInitExpr(AST.InitExpr initExpr) {
         return objPtr.unkeep();
     }
 
-    private Node newArray(TypeStruct ary, Node len) {
+    private Node newArray(TypeStruct ary, Node arrayLen) {
         int base = ary.aryBase ();
-        int scale= ary.aryScale();
-        Node size = peep(new AddNode(con(base),peep(new ShlNode(len.keep(),con(scale)))));
-        return newStruct(ary,size);
+        int scale = ary.aryScale();
+        // array size = base + len << scale
+        Node size = peep(new AddNode(con(base),peep(new ShlNode(arrayLen.keep(),con(scale)))));
+        Node ptr = newStruct(ary,size).keep();
+        // arrays are structs with two fields
+        // first field is length
+        // second field is [] data
+        Field[] fs = ary._fields;
+        // store length as int32
+        Node mem = memAlias(fs[0]._alias);
+        Node st = new StoreNode(fs[0]._fname,fs[0]._alias,fs[0]._type,mem,ptr,con(ary.offset(0)),arrayLen.unkeep(),true).peephole();
+        memAlias(fs[0]._alias,st);
+        return ptr.unkeep();
     }
+
     /**
      * Return a NewNode initialized memory.
      * @param obj is the declared type, with GLB fields
@@ -586,6 +616,7 @@ private Node compileUnaryExpr(AST.UnaryExpr unaryExpr) {
             }
             // Maybe below we should explicitly set Int
             case "!": return peep(new NotNode(compileExpr(unaryExpr.expr)));
+            case "#": return compileArrayLengthExpr(unaryExpr.expr, unaryExpr.lineNumber);
             default: throw new CompilerException("Invalid unary op", unaryExpr.lineNumber);
         }
     }
diff --git a/seaofnodes/src/test/cases/array/array.ez b/seaofnodes/src/test/cases/array/array.ez
new file mode 100644
index 0000000..eca7280
--- /dev/null
+++ b/seaofnodes/src/test/cases/array/array.ez
@@ -0,0 +1,3 @@
+func foo()->Int {
+  return #new [Int]{42,84}
+}
diff --git a/seaofnodes/src/test/cases/array/array.ez_ir b/seaofnodes/src/test/cases/array/array.ez_ir
new file mode 100644
index 0000000..83a1f88
--- /dev/null
+++ b/seaofnodes/src/test/cases/array/array.ez_ir
@@ -0,0 +1,21 @@
+START:                            [[   ]]
+   4 Start   ____ ____ ____       [[     7   18    3  ]]  [  Ctrl, #TOP, int]
+
+L3:                               [[  START      ]]
+   3 foo     ____    4            [[     6   17   11   10   14    8   13    5   16    2  ]]  Ctrl
+   6 $mem       3    7            [[     5   10   10  ]]  #BOT
+  17 $rpc       3   18            [[     2       ]]  $[ALL]
+  11 #24        3                 [[    10       ]]  24
+  10 new_ary    3   11    6    6  [[     9   12   15  ]]  [  Ctrl, *![int], #2:u32, #3:int]
+   9 $2        10                 [[     8       ]]  #2:u32
+  12 [int]     10                 [[     8   14   13  ]]  *[int]
+  15 $3        10                 [[    14       ]]  #3:int
+  14 st8        3   15   12 ____ ____  [[    13  ]]  #3:int
+  13 st8        3   14   12 ____ ____  [[     5  ]]  #3:int
+   8 st4        3    9   12 ____ ____  [[     5  ]]  #2:u32
+  16 #2         3                 [[     2       ]]  2
+   5 ALLMEM     3    6    8   13  [[     2       ]]  #BOT
+   2 Return     3    5   16   17  [[     1       ]]  [  Ctrl, #BOT, 2]
+
+L1:                               [[   ]]
+   1 Stop       2                 [[             ]]  Bot
diff --git a/seaofnodes/src/test/cases/array/array.ez_out b/seaofnodes/src/test/cases/array/array.ez_out
new file mode 100644
index 0000000..0530680
--- /dev/null
+++ b/seaofnodes/src/test/cases/array/array.ez_out
@@ -0,0 +1,15 @@
+---foo { -> int #0}---------------------------
+0000 4883EC08    subi  rsp -= #8
+0004 BE18000000  ldi   rsi = #24
+0009 BF01000000  alloc ldi   rcx = #1
+000E E800000000  call  #calloc
+0013 48C740082A  st8   [rax+8],#42
+0018 000000
+001B C700020000  st4   [rax],#2
+0020 00
+0021 48C7401054  st8   [rax+16],#84
+0026 000000
+0029 B802000000  ldi   rax = #2
+002E 4883C408C3  addi  rsp += #8
+0033             ret
+---{ -> int #0}---------------------------
\ No newline at end of file
diff --git a/seaofnodes/src/test/cases/array/array.smp b/seaofnodes/src/test/cases/array/array.smp
new file mode 100644
index 0000000..d535448
--- /dev/null
+++ b/seaofnodes/src/test/cases/array/array.smp
@@ -0,0 +1,6 @@
+var foo = {->
+  var a = new int[2];
+  a[0] = 42;
+  a[1] = 84;
+  return a#;
+};
\ No newline at end of file
diff --git a/seaofnodes/src/test/cases/array/array.smp_ir b/seaofnodes/src/test/cases/array/array.smp_ir
new file mode 100644
index 0000000..83a1f88
--- /dev/null
+++ b/seaofnodes/src/test/cases/array/array.smp_ir
@@ -0,0 +1,21 @@
+START:                            [[   ]]
+   4 Start   ____ ____ ____       [[     7   18    3  ]]  [  Ctrl, #TOP, int]
+
+L3:                               [[  START      ]]
+   3 foo     ____    4            [[     6   17   11   10   14    8   13    5   16    2  ]]  Ctrl
+   6 $mem       3    7            [[     5   10   10  ]]  #BOT
+  17 $rpc       3   18            [[     2       ]]  $[ALL]
+  11 #24        3                 [[    10       ]]  24
+  10 new_ary    3   11    6    6  [[     9   12   15  ]]  [  Ctrl, *![int], #2:u32, #3:int]
+   9 $2        10                 [[     8       ]]  #2:u32
+  12 [int]     10                 [[     8   14   13  ]]  *[int]
+  15 $3        10                 [[    14       ]]  #3:int
+  14 st8        3   15   12 ____ ____  [[    13  ]]  #3:int
+  13 st8        3   14   12 ____ ____  [[     5  ]]  #3:int
+   8 st4        3    9   12 ____ ____  [[     5  ]]  #2:u32
+  16 #2         3                 [[     2       ]]  2
+   5 ALLMEM     3    6    8   13  [[     2       ]]  #BOT
+   2 Return     3    5   16   17  [[     1       ]]  [  Ctrl, #BOT, 2]
+
+L1:                               [[   ]]
+   1 Stop       2                 [[             ]]  Bot
diff --git a/seaofnodes/src/test/cases/array/array.smp_out b/seaofnodes/src/test/cases/array/array.smp_out
new file mode 100644
index 0000000..ad51d7b
--- /dev/null
+++ b/seaofnodes/src/test/cases/array/array.smp_out
@@ -0,0 +1,15 @@
+---foo { -> 2 #0}---------------------------
+0000 4883EC08    subi  rsp -= #8
+0004 BE18000000  ldi   rsi = #24
+0009 BF01000000  alloc ldi   rcx = #1
+000E E800000000  call  #calloc
+0013 48C740082A  st8   [rax+8],#42
+0018 000000
+001B C700020000  st4   [rax],#2
+0020 00
+0021 48C7401054  st8   [rax+16],#84
+0026 000000
+0029 B802000000  ldi   rax = #2
+002E 4883C408C3  addi  rsp += #8
+0033             ret
+---{ -> 2 #0}---------------------------
\ No newline at end of file
diff --git a/seaofnodes/src/test/cases/array2/array.ez b/seaofnodes/src/test/cases/array2/array.ez
new file mode 100644
index 0000000..af8ecee
--- /dev/null
+++ b/seaofnodes/src/test/cases/array2/array.ez
@@ -0,0 +1,6 @@
+func foo()->[Float] {
+  return new [Float]{4.2,8.4}
+}
+func bar()->Int {
+	return #foo()
+}
\ No newline at end of file
diff --git a/seaofnodes/src/test/cases/array2/array.ez_ir b/seaofnodes/src/test/cases/array2/array.ez_ir
new file mode 100644
index 0000000..a08c246
--- /dev/null
+++ b/seaofnodes/src/test/cases/array2/array.ez_ir
@@ -0,0 +1,38 @@
+START:                            [[   ]]
+   4 Start   ____ ____ ____       [[     7   19   24    3  ]]  [  Ctrl, #TOP, int]
+
+L3:                               [[  START      ]]
+   3 foo     ____    4            [[     6   18   11   16   17   10   14   13    8    5    2  ]]  Ctrl
+   6 $mem       3    7            [[     5   10   10  ]]  #BOT
+  18 $rpc       3   19            [[     2       ]]  $[ALL]
+  16 #4.2       3                 [[    14       ]]  4.2
+  11 #24        3                 [[    10       ]]  24
+  17 #8.4       3                 [[    13       ]]  8.4
+  14 st8        3   15   12 ____   16  [[    13  ]]  #5:flt
+  13 st8        3   14   12 ____   17  [[     5  ]]  #5:flt
+  10 new_ary    3   11    6    6  [[     9   12   15  ]]  [  Ctrl, *![flt], #4:u32, #5:flt]
+   9 $4        10                 [[     8       ]]  #4:u32
+  12 [flt]     10                 [[     8   14   13    2  ]]  *[flt]
+  15 $5        10                 [[    14       ]]  #5:flt
+   8 st4        3    9   12 ____ ____  [[     5  ]]  #4:u32
+   5 ALLMEM     3    6 ____ ____    8   13  [[     2  ]]  #BOT
+   2 Return     3    5   12   18  [[     1       ]]  [  Ctrl, #BOT, *![flt]]
+
+L24:                              [[  START      ]]
+  24 bar     ____    4            [[    25   29   23  ]]  Ctrl
+  25 $mem      24    7            [[    23       ]]  #BOT
+  29 $rpc      24   19            [[    20       ]]  $[ALL]
+  23 call      24   25            [[    22       ]]  Ctrl
+
+L22:                              [[  L24        ]]
+  22 CallEnd   23                 [[    21   26   28  ]]  [  Ctrl, #BOT, *![flt]]
+  28 #2        22                 [[    27       ]]  *[flt]
+  26 $mem      22                 [[    20   27  ]]  #BOT
+
+L21:                              [[  L22        ]]
+  21 $ctrl     22                 [[    27   20  ]]  Ctrl
+  27 ld4       21   26   28 ____  [[    20       ]]  u32
+  20 Return    21   26   27   29  [[     1       ]]  [  Ctrl, #BOT, u32]
+
+L1:                               [[   ]]
+   1 Stop       2   20            [[             ]]  Bot
diff --git a/seaofnodes/src/test/cases/array2/array.ez_out b/seaofnodes/src/test/cases/array2/array.ez_out
new file mode 100644
index 0000000..e7b9df2
--- /dev/null
+++ b/seaofnodes/src/test/cases/array2/array.ez_out
@@ -0,0 +1,24 @@
+---foo { -> *![flt] #0}---------------------------
+0000 4883EC08    subi  rsp -= #8
+0004 BE18000000  ldi   rsi = #24
+0009 BF01000000  alloc ldi   rcx = #1
+000E E800000000  call  #calloc
+0013 F20F100500  ld8   xmm0 = #4.2
+0018 000000
+001B F20F114008  st8   [rax+8],xmm0
+0020 F20F100500  ld8   xmm0 = #8.4
+0025 000000
+0028 F20F114010  st8   [rax+16],xmm0
+002D C700020000  st4   [rax],#2
+0032 00
+0033 4883C408C3  addi  rsp += #8
+0038             ret
+---{ -> *![flt] #0}---------------------------
+
+---bar { -> int #1}---------------------------
+0040 4883EC08    subi  rsp -= #8
+0044 E8B7FFFFFF  call  foo
+0049 8B00        ld4   rax,[rax]
+004B 4883C408C3  addi  rsp += #8
+0050             ret
+---{ -> int #1}---------------------------
diff --git a/seaofnodes/src/test/cases/array2/array.smp b/seaofnodes/src/test/cases/array2/array.smp
new file mode 100644
index 0000000..c9e7520
--- /dev/null
+++ b/seaofnodes/src/test/cases/array2/array.smp
@@ -0,0 +1,9 @@
+val foo = {->
+  var a = new flt[2];
+  a[0] = 4.2;
+  a[1] = 8.4;
+  return a;
+};
+val bar = { ->
+	return foo()#;
+};
\ No newline at end of file
diff --git a/seaofnodes/src/test/cases/array2/array.smp_ir b/seaofnodes/src/test/cases/array2/array.smp_ir
new file mode 100644
index 0000000..dfddaca
--- /dev/null
+++ b/seaofnodes/src/test/cases/array2/array.smp_ir
@@ -0,0 +1,38 @@
+START:                            [[   ]]
+   7 Start   ____ ____ ____       [[     9   25   11    6  ]]  [  Ctrl, #TOP, int]
+
+L6:                               [[  START      ]]
+   6 bar     ____    7            [[     8   30    5  ]]  Ctrl
+   8 $mem       6    9            [[     5       ]]  #BOT
+  30 $rpc       6   25            [[     2       ]]  $[ALL]
+   5 call       6    8            [[     4       ]]  Ctrl
+
+L11:                              [[  START      ]]
+  11 foo     ____    7            [[    13   24   17   22   23   16   20   19   14   12   10  ]]  Ctrl
+  13 $mem      11    9            [[    12   16   16  ]]  #BOT
+  24 $rpc      11   25            [[    10       ]]  $[ALL]
+  22 #4.2      11                 [[    20       ]]  4.2
+  17 #24       11                 [[    16       ]]  24
+  23 #8.4      11                 [[    19       ]]  8.4
+  20 st8       11   21   18 ____   22  [[    19  ]]  #3:flt
+  19 st8       11   20   18 ____   23  [[    12  ]]  #3:flt
+  16 new_ary   11   17   13   13  [[    15   18   21  ]]  [  Ctrl, *![flt], #2:u32, #3:flt]
+  15 $2        16                 [[    14       ]]  #2:u32
+  18 [flt]     16                 [[    14   20   19   10  ]]  *[flt]
+  21 $3        16                 [[    20       ]]  #3:flt
+  14 st4       11   15   18 ____ ____  [[    12  ]]  #2:u32
+  12 ALLMEM    11   13   14   19  [[    10       ]]  #BOT
+  10 Return    11   12   18   24  [[     1       ]]  [  Ctrl, #BOT, *![flt]]
+
+L4:                               [[  L6         ]]
+   4 CallEnd    5                 [[     3   27   29  ]]  [  Ctrl, #BOT, *![flt]]
+  29 #2         4                 [[    28       ]]  *[flt]
+  27 $mem       4                 [[     2   28  ]]  #BOT
+
+L3:                               [[  L4         ]]
+   3 $ctrl      4                 [[    28    2  ]]  Ctrl
+  28 ld4        3   27   29 ____  [[     2       ]]  u32
+   2 Return     3   27   28   30  [[     1       ]]  [  Ctrl, #BOT, u32]
+
+L1:                               [[   ]]
+   1 Stop       2   10            [[             ]]  Bot
diff --git a/seaofnodes/src/test/cases/array2/array.smp_out b/seaofnodes/src/test/cases/array2/array.smp_out
new file mode 100644
index 0000000..a853e66
--- /dev/null
+++ b/seaofnodes/src/test/cases/array2/array.smp_out
@@ -0,0 +1,27 @@
+---bar { -> u32 #1}---------------------------
+0000 4883EC08    subi  rsp -= #8
+0004 E807000000  call  foo
+0009 8B00        ld4   rax,[rax]
+000B 4883C408C3  addi  rsp += #8
+0010             ret
+---{ -> u32 #1}---------------------------
+
+---foo { -> *![flt] #0}---------------------------
+0010 4883EC08    subi  rsp -= #8
+0014 BE18000000  ldi   rsi = #24
+0019 BF01000000  alloc ldi   rcx = #1
+001E E800000000  call  #calloc
+0023 F20F100500  ld8   xmm0 = #4.2
+0028 000000
+002B F20F114008  st8   [rax+8],xmm0
+0030 F20F100500  ld8   xmm0 = #8.4
+0035 000000
+0038 F20F114010  st8   [rax+16],xmm0
+003D C700020000  st4   [rax],#2
+0042 00
+0043 4883C408C3  addi  rsp += #8
+0048             ret
+---{ -> *![flt] #0}---------------------------
+--- Constant Pool ------
+0050  0000000000000000 4.2
+0058  0000000000000000 8.4
diff --git a/seaofnodes/src/test/java/com/compilerprogramming/ezlang/compiler/TestSONTypes.java b/seaofnodes/src/test/java/com/compilerprogramming/ezlang/compiler/TestSONTypes.java
index e7e293f..de1e2f7 100644
--- a/seaofnodes/src/test/java/com/compilerprogramming/ezlang/compiler/TestSONTypes.java
+++ b/seaofnodes/src/test/java/com/compilerprogramming/ezlang/compiler/TestSONTypes.java
@@ -161,6 +161,15 @@ func foo()->Int {
         compileSrc(src);
     }
 
+    @Test
+    public void testArrayLengthUnaryOperator() {
+        String src = """
+func foo()->Int {
+  return #new [Int]{42,84};
+}
+""";
+        compileSrc(src);
+    }
     @Test
     public void test17() {
         String src = """
@@ -194,7 +203,7 @@ func foo()->Int {
         compileSrc(src);
     }
 
-        static void testCPU( String src, String cpu, String os, int spills, String stop ) {
+    static void testCPU( String src, String cpu, String os, int spills, String stop ) {
         CodeGen code = new CodeGen(src);
         code.parse().opto().typeCheck().loopTree().instSelect(cpu,os).GCM().localSched().regAlloc().encode();
         int delta = spills>>3;
diff --git a/semantic/src/main/java/com/compilerprogramming/ezlang/semantic/NullableAnalysis.java b/semantic/src/main/java/com/compilerprogramming/ezlang/semantic/NullableAnalysis.java
index 8d98562..a5e604f 100644
--- a/semantic/src/main/java/com/compilerprogramming/ezlang/semantic/NullableAnalysis.java
+++ b/semantic/src/main/java/com/compilerprogramming/ezlang/semantic/NullableAnalysis.java
@@ -199,6 +199,11 @@ else if (initExpr.newExpr.type instanceof EZType.EZTypeArray arrayType) {
         }
 
         if (e instanceof AST.UnaryExpr un) {
+            if (un.op.str.equals("#")) {
+                checkDereference(un.expr, facts);
+                return factFromType(un.type);
+            }
+
             LatticeElement v = analyzeExpr(un.expr, facts);
 
             if (un.op.str.equals("-")) {
diff --git a/semantic/src/main/java/com/compilerprogramming/ezlang/semantic/SemaAssignTypes.java b/semantic/src/main/java/com/compilerprogramming/ezlang/semantic/SemaAssignTypes.java
index 10c9c76..605c6de 100644
--- a/semantic/src/main/java/com/compilerprogramming/ezlang/semantic/SemaAssignTypes.java
+++ b/semantic/src/main/java/com/compilerprogramming/ezlang/semantic/SemaAssignTypes.java
@@ -98,7 +98,17 @@ public void exit(AST.UnaryExpr unaryExpr) {
             return;
         }
         validType(unaryExpr.expr.type, false, unaryExpr.lineNumber);
-        if (unaryExpr.expr.type instanceof EZType.EZTypeInteger) {
+        if (unaryExpr.op.str.equals("#")) {
+            if (unaryExpr.expr.type instanceof EZType.EZTypeArray ||
+                    (unaryExpr.expr.type instanceof EZType.EZTypeNullable nullable && nullable.baseType instanceof EZType.EZTypeArray)) {
+                unaryExpr.type = typeDictionary.INT;
+            }
+            else {
+                throw new CompilerException("Unary operator " + unaryExpr.op + " not supported for operand", unaryExpr.lineNumber);
+            }
+        }
+        else if (unaryExpr.expr.type instanceof EZType.EZTypeInteger &&
+                (unaryExpr.op.str.equals("-") || unaryExpr.op.str.equals("!"))) {
             unaryExpr.type = unaryExpr.expr.type;
         }
         else if (unaryExpr.expr.type instanceof EZType.EZTypeFloat && unaryExpr.op.str.equals("-")) {
diff --git a/semantic/src/test/java/com/compilerprogramming/ezlang/semantic/TestNullAnalysis.java b/semantic/src/test/java/com/compilerprogramming/ezlang/semantic/TestNullAnalysis.java
index 860b1ec..2728b2f 100644
--- a/semantic/src/test/java/com/compilerprogramming/ezlang/semantic/TestNullAnalysis.java
+++ b/semantic/src/test/java/com/compilerprogramming/ezlang/semantic/TestNullAnalysis.java
@@ -200,6 +200,28 @@ func test(arg: [Int]?)->Int {
         analyze(src, "test");
     }
 
+    @Test(expected = CompilerException.class)
+    public void nullableArrayLength() {
+        String src = """
+    func test(arg: [Int]?)->Int {
+        return #arg;
+    }
+""";
+        analyze(src, "test");
+    }
+
+    @Test
+    public void guardedNullableArrayLength() {
+        String src = """
+    func test(arg: [Int]?)->Int {
+        if (arg != null) {
+            return #arg;
+        }
+        return 0;
+    }
+""";
+        analyze(src, "test");
+    }
     @Test
     public void guardedNullableFieldStore() {
         String src = """
diff --git a/stackvm/src/main/java/com/compilerprogramming/ezlang/compiler/CompiledFunction.java b/stackvm/src/main/java/com/compilerprogramming/ezlang/compiler/CompiledFunction.java
index f6e7be2..6ef7919 100644
--- a/stackvm/src/main/java/com/compilerprogramming/ezlang/compiler/CompiledFunction.java
+++ b/stackvm/src/main/java/com/compilerprogramming/ezlang/compiler/CompiledFunction.java
@@ -418,6 +418,7 @@ private boolean compileUnaryExpr(AST.UnaryExpr unaryExpr) {
         switch (unaryExpr.op.str) {
             case "-" -> opCode = unaryExpr.type instanceof EZType.EZTypeFloat ? Instruction.NEG_F : Instruction.NEG_I;
             case "!" -> opCode = Instruction.NOT;
+            case "#" -> opCode = Instruction.LENGTH;
             default -> throw new CompilerException("Invalid binary op", unaryExpr.lineNumber);
         }
         code(new Instruction.UnaryOp(opCode));
diff --git a/stackvm/src/main/java/com/compilerprogramming/ezlang/compiler/Instruction.java b/stackvm/src/main/java/com/compilerprogramming/ezlang/compiler/Instruction.java
index a2fcbc2..670e2ad 100644
--- a/stackvm/src/main/java/com/compilerprogramming/ezlang/compiler/Instruction.java
+++ b/stackvm/src/main/java/com/compilerprogramming/ezlang/compiler/Instruction.java
@@ -36,6 +36,7 @@ public class Instruction {
     public static final int MUL_F = 28;
     public static final int DIV_F = 29;
     public static final int NEG_F = 30;
+    public static final int LENGTH = 31;
 
     static final String[] opNames = {
         "ret",
@@ -68,7 +69,8 @@ public class Instruction {
         "subf",
         "mulf",
         "divf",
-        "negf"
+        "negf",
+        "length"
     };
 
     public final int opcode;
diff --git a/stackvm/src/test/java/com/compilerprogramming/ezlang/compiler/TestCompiler.java b/stackvm/src/test/java/com/compilerprogramming/ezlang/compiler/TestCompiler.java
index 2d828ee..ad7f28c 100644
--- a/stackvm/src/test/java/com/compilerprogramming/ezlang/compiler/TestCompiler.java
+++ b/stackvm/src/test/java/com/compilerprogramming/ezlang/compiler/TestCompiler.java
@@ -664,4 +664,20 @@ func foo()->Int
 """, result);
     }
 
+    @Test
+    public void testArrayLengthUnaryOperator() {
+        String src = """
+                func foo(a: [Int])->Int {
+                    return #a;
+                }
+                """;
+        String result = compileSrc(src);
+        Assert.assertEquals("""
+L0:
+	load 0
+	length
+	jump L1
+L1:
+""", result);
+    }
 }