diff --git a/compiler/middle/borrow_checker.ts b/compiler/middle/borrow_checker.ts
index 8cb536d..fc58f99 100644
--- a/compiler/middle/borrow_checker.ts
+++ b/compiler/middle/borrow_checker.ts
@@ -170,9 +170,6 @@ class LocalChecker {
     }
 
     private markSrc(src: RValue) {
-        if (src.type === "local") {
-            throw new Error("should be 'copy' or 'move'");
-        }
         if (
             (src.type !== "copy" && src.type !== "move") ||
             src.id !== this.local.id
diff --git a/compiler/middle/elim_unused_local.ts b/compiler/middle/elim_unused_local.ts
index 67b551a..3feca87 100644
--- a/compiler/middle/elim_unused_local.ts
+++ b/compiler/middle/elim_unused_local.ts
@@ -73,7 +73,7 @@ class EliminateUnusedLocalsFnPass {
     }
 
     private markUsed(local: RValue) {
-        if (local.type !== "local") {
+        if (local.type !== "copy" && local.type !== "move") {
             return;
         }
         this.locals = this.locals.filter((lid) => lid !== local.id);
diff --git a/compiler/middle/explicit_move_copy.ts b/compiler/middle/explicit_move_copy.ts
index 533bec4..6927220 100644
--- a/compiler/middle/explicit_move_copy.ts
+++ b/compiler/middle/explicit_move_copy.ts
@@ -23,7 +23,7 @@ class LocalExpliciter {
     }
 
     private explicitSrc(src: RValue): RValue {
-        if (src.type !== "local" || src.id !== this.local.id) {
+        if (src.type !== "move" || src.id !== this.local.id) {
             return src;
         }
         return this.copyable
diff --git a/compiler/middle/lower_ast.ts b/compiler/middle/lower_ast.ts
index 8c1b408..c0ae402 100644
--- a/compiler/middle/lower_ast.ts
+++ b/compiler/middle/lower_ast.ts
@@ -509,5 +509,5 @@ class FnAstLowerer {
 }
 
 function local(id: LocalId): RValue {
-    return { type: "local", id };
+    return { type: "move", id };
 }
diff --git a/compiler/middle/mir.ts b/compiler/middle/mir.ts
index 128e384..d6585cc 100644
--- a/compiler/middle/mir.ts
+++ b/compiler/middle/mir.ts
@@ -45,7 +45,6 @@ export type OpKind =
     | { type: "ref_mut"; dst: L; src: L }
     | { type: "ptr"; dst: L; src: L }
     | { type: "ptr_mut"; dst: L; src: L }
-    | { type: "drop"; src: L }
     | { type: "deref"; dst: L; src: R }
     | { type: "assign_deref"; subject: R; src: R }
     | { type: "field"; dst: L; subject: R; ident: string }
@@ -67,7 +66,6 @@ export type TerKind =
 
 export type RValue =
     | { type: "error" }
-    | { type: "local"; id: BlockId }
     | { type: "copy"; id: BlockId }
     | { type: "move"; id: BlockId }
     | { type: "null" }
@@ -123,7 +121,6 @@ export function replaceBlockSrcs(
             case "ref_mut":
             case "ptr":
             case "ptr_mut":
-            case "drop":
                 break;
             case "deref":
                 ok.src = replace(ok.src);
@@ -190,7 +187,6 @@ export function visitBlockSrcs(
             case "ref_mut":
             case "ptr":
             case "ptr_mut":
-            case "drop":
                 break;
             case "deref":
                 visitor(ok.src, op, i);
@@ -307,9 +303,6 @@ export function printMir(mir: Mir) {
                     case "ptr_mut":
                         l(`_${k.dst} = *mut _${k.src};`);
                         break;
-                    case "drop":
-                        l(`drop _${k.src};`);
-                        break;
                     case "deref":
                         l(`_${k.dst} = *${r(k.src)};`);
                         break;
@@ -372,8 +365,6 @@ export function rvalueToString(rvalue: RValue): string {
     switch (rvalue.type) {
         case "error":
             return `<error>`;
-        case "local":
-            return `_${rvalue.id}`;
         case "copy":
             return `copy _${rvalue.id}`;
         case "move":
diff --git a/examples/calculator.slg b/examples/calculator.slg
new file mode 100644
index 0000000..d9021e1
--- /dev/null
+++ b/examples/calculator.slg
@@ -0,0 +1,164 @@
+mod std;
+
+type_alias Tok: struct {
+    type: string,
+    value: string,
+};
+
+fn lex(text: string) -> [Tok] {
+    let i = 0;
+    let len = std::string_length(text);
+    
+    let toks = std::array_new::<Tok>();
+
+    while i < len {
+        if std::string_contains(" \t\n", text[i]) {
+            i += 1;
+            if i >= len {
+                break;
+            }
+        }
+        if text[i] >= '1' and text[i] <= '9' {
+            let value = std::ctos(text[i]);
+            i += 1;
+            while i < len and text[i] >= '0' and text[i] <= '9' {
+                value = std::string_push_char(value, text[i]);
+                i += 1;
+            }
+            let tok = struct { type: "int", value: value };
+            std::array_push(toks, tok);
+        } else if text[i] == '0' {
+            i += 1;
+            let tok = struct { type: "int", value: "0" };
+            std::array_push(toks, tok);
+        } else if text[i] == '+' {
+            i += 1;
+            let tok = struct { type: "+", value: "+" };
+            std::array_push(toks, tok);
+        } else if text[i] == '-' {
+            i += 1;
+            let tok = struct { type: "-", value: "-" };
+            std::array_push(toks, tok);
+        } else if text[i] == '*' {
+            i += 1;
+            let tok = struct { type: "*", value: "*" };
+            std::array_push(toks, tok);
+        } else if text[i] == '/' {
+            i += 1;
+            let tok = struct { type: "/", value: "/" };
+            std::array_push(toks, tok);
+        } else if text[i] == '(' {
+            i += 1;
+            let tok = struct { type: "(", value: "(" };
+            std::array_push(toks, tok);
+        } else if text[i] == ')' {
+            i += 1;
+            let tok = struct { type: ")", value: ")" };
+            std::array_push(toks, tok);
+        } else {
+            std::println("error: illegal character '" + std::ctos(text[i]) + "'");
+            i += 1;
+        }
+    }
+    
+    toks
+}
+
+type_alias Calc: struct {
+    toks: [Tok],
+    toks_len: int,
+    i: int,
+};
+
+fn calc_new(text: string) -> Calc {
+    let toks = lex(text);
+    let toks_len = std::array_length(toks);
+    struct { toks: toks, toks_len: toks_len, i: 0 }
+}
+
+fn calc_expr(self: Calc) -> int {
+    calc_add_sub(self)
+}
+
+fn calc_add_sub(self: Calc) -> int {
+    let left = calc_mul_div(self);
+    loop {
+        if self.toks[self.i].type == "+" {
+            self.i += 1;
+            let right = calc_mul_div(self);
+            left = left + right;
+        } else if self.toks[self.i].type == "-" {
+            self.i += 1;
+            let right = calc_mul_div(self);
+            left = left - right;
+        } else {
+            break;
+        }
+    }
+    left
+}
+
+fn calc_mul_div(self: Calc) -> int {
+    let left = calc_unary(self);
+    loop {
+        if self.toks[self.i].type == "*" {
+            self.i += 1;
+            let right = calc_unary(self);
+            left = left * right;
+        } else if self.toks[self.i].type == "/" {
+            self.i += 1;
+            let right = calc_unary(self);
+            left = left / right;
+        } else {
+            break;
+        }
+    }
+    left
+    
+}
+
+fn calc_unary(self: Calc) -> int {
+    if self.toks[self.i].type == "-" {
+        self.i += 1;
+        let subject = calc_unary(self);
+        -subject
+    } else {
+        calc_operand(self)
+    }
+}
+
+fn calc_operand(self: Calc) -> int {
+    if self.i >= self.toks_len {
+        std::println("error: expected expr");
+        0
+    } else if self.toks[self.i].type == "int" {
+        let val = std::stoi(self.toks[self.i].value);
+        self.i += 1;
+        val
+    } else if self.toks[self.i].type == "(" {
+        self.i += 1;
+        let val = calc_expr(self);
+        if self.i >= self.toks_len or self.toks[self.i].type != ")" {
+            std::println("error: missing ')'");
+            return 0;
+        }
+        self.i += 1;
+        val
+    } else {
+        std::println("error: expected expr");
+        self.i += 1;
+        0
+    }
+}
+
+fn main() {
+    loop {
+        let line = std::input("> ");
+        if line == "exit" {
+            break;
+        }
+        let calc = calc_new(line);
+        let val = calc_expr(calc);
+        std::println(line);
+    }
+}