diff --git a/compiler/Checker.ts b/compiler/Checker.ts
index f004723..92525cc 100644
--- a/compiler/Checker.ts
+++ b/compiler/Checker.ts
@@ -196,17 +196,19 @@ export class Checker {
                 return;
             }
             case "sym": {
-                if (stmt.kind.subject.kind.defType !== "let") {
+                if (stmt.kind.subject.kind.sym.type !== "let") {
                     this.report("cannot only assign to let-symbol", pos);
                     return { type: "error" };
                 }
-                if (!vtypesEqual(stmt.kind.subject.kind.param!.vtype!, value)) {
+                if (
+                    !vtypesEqual(stmt.kind.subject.kind.sym.param.vtype!, value)
+                ) {
                     this.report(
                         `cannot assign to incompatible type` +
                             `, got '${vtypeToString(value)}'` +
                             `, expected '${
                                 vtypeToString(
-                                    stmt.kind.subject.kind.param!.vtype!,
+                                    stmt.kind.subject.kind.sym.param.vtype!,
                                 )
                             }'`,
                         pos,
@@ -266,12 +268,11 @@ export class Checker {
         if (expr.kind.type !== "sym") {
             throw new Error();
         }
-        const pos = expr.pos;
-        switch (expr.kind.defType) {
+        switch (expr.kind.sym.type) {
             case "let":
-                return expr.kind.param?.vtype!;
+                return expr.kind.sym.param.vtype!;
             case "fn": {
-                const fnStmt = expr.kind.stmt!;
+                const fnStmt = expr.kind.sym.stmt!;
                 if (fnStmt.kind.type !== "fn") {
                     throw new Error();
                 }
@@ -283,9 +284,13 @@ export class Checker {
                 return { type: "fn", params, returnType };
             }
             case "fn_param":
-                return expr.kind.param!.vtype!;
+                return expr.kind.sym.param.vtype!;
             case "builtin":
-                throw new Error();
+            case "let_static":
+            case "closure":
+                throw new Error(
+                    `not implemented, sym type '${expr.kind.sym.type}'`,
+                );
         }
     }
 
diff --git a/compiler/Lowerer.ts b/compiler/Lowerer.ts
index 2239a17..c7525a5 100644
--- a/compiler/Lowerer.ts
+++ b/compiler/Lowerer.ts
@@ -1,93 +1,83 @@
+import { Builtins } from "./arch.ts";
 import { BinaryType, Expr, Stmt } from "./ast.ts";
+import { LocalLeaf, Locals, LocalsFnRoot } from "./lowerer_locals.ts";
 import { Ops } from "./mod.ts";
-import { VType } from "./vtypes.ts";
-
-interface Locals {
-    reserveId(id: number): void;
-    allocSym(ident: string): void;
-    symId(ident: string): number;
-}
-
-class LocalsFnRoot implements Locals {
-    private localsAmount = 0;
-    private localIdCounter = 0;
-    private symLocalMap: { [key: string]: number } = {};
-
-    constructor(private parent?: Locals) {
-    }
-
-    reserveId(id: number): void {
-        this.localsAmount = Math.max(id + 1, this.localsAmount);
-    }
-
-    allocSym(ident: string) {
-        this.symLocalMap[ident] = this.localIdCounter;
-        this.localIdCounter++;
-        this.reserveId(this.localIdCounter);
-    }
-
-    symId(ident: string): number {
-        if (ident in this.symLocalMap) {
-            return this.symLocalMap[ident];
-        }
-        if (this.parent) {
-            return this.parent.symId(ident);
-        }
-        throw new Error(`undefined symbol '${ident}'`);
-    }
-}
-
-class LocalLeaf implements Locals {
-    private localIdCounter = 0;
-    private symLocalMap: { [key: string]: number } = {};
-
-    constructor(private parent: Locals) {
-    }
-
-    reserveId(id: number): void {
-        this.parent.reserveId(id);
-    }
-
-    allocSym(ident: string) {
-        this.symLocalMap[ident] = this.localIdCounter;
-        this.localIdCounter++;
-        this.reserveId(this.localIdCounter);
-    }
-
-    symId(ident: string): number {
-        if (ident in this.symLocalMap) {
-            return this.symLocalMap[ident];
-        }
-        return this.parent.symId(ident);
-    }
-}
+import { VType, vtypeToString } from "./vtypes.ts";
 
 export class Lowerer {
     private program: number[] = [];
-    private locals = new LocalsFnRoot();
+    private locals: Locals = new LocalsFnRoot();
+    private fnStmtIdAddrMap: { [key: number]: number } = {};
 
-    lower(stmts: Stmt[]) {
+    public lower(stmts: Stmt[]) {
         for (const stmt of stmts) {
-            this.lowerStmt(stmt);
+            this.lowerStaticStmt(stmt);
         }
     }
 
-    lowerStmt(stmt: Stmt) {
+    public finish(): number[] {
+        return this.program;
+    }
+
+    private lowerStaticStmt(stmt: Stmt) {
+        switch (stmt.kind.type) {
+            case "fn":
+                return this.lowerFnStmt(stmt);
+            case "error":
+            case "break":
+            case "return":
+            case "let":
+            case "assign":
+            case "expr":
+        }
+        throw new Error(`unhandled static statement '${stmt.kind.type}'`);
+    }
+
+    private lowerStmt(stmt: Stmt) {
         switch (stmt.kind.type) {
             case "error":
             case "break":
             case "return":
-            case "fn":
                 break;
+            case "fn":
+                return this.lowerFnStmt(stmt);
             case "let":
                 return this.lowerLetStmt(stmt);
             case "assign":
+                break;
             case "expr":
+                this.lowerExpr(stmt.kind.expr);
+                this.program.push(Ops.Pop);
+                return;
         }
-        throw new Error(`Unhandled stmt ${stmt.kind.type}`);
+        throw new Error(`unhandled stmt '${stmt.kind.type}'`);
     }
 
-    lowerLetStmt(stmt: Stmt) {
+    private lowerFnStmt(stmt: Stmt) {
+        if (stmt.kind.type !== "fn") {
+            throw new Error();
+        }
+        const outerLocals = this.locals;
+        this.locals = new LocalsFnRoot(outerLocals);
+        const outerProgram = this.program;
+        this.program = [];
+
+        for (const { ident } of stmt.kind.params) {
+            this.locals.allocSym(ident);
+            this.program.push(
+                Ops.StoreLocal,
+                this.locals.symId(ident),
+            );
+        }
+        this.lowerExpr(stmt.kind.body);
+        this.program.push(Ops.Return);
+
+        this.locals = outerLocals;
+        outerProgram.push(...this.program);
+        this.program = outerProgram;
+    }
+
+    private lowerLetStmt(stmt: Stmt) {
         if (stmt.kind.type !== "let") {
             throw new Error();
         }
@@ -97,55 +87,88 @@ export class Lowerer {
         this.program.push(this.locals.symId(stmt.kind.param.ident));
     }
 
-    lowerExpr(expr: Expr) {
+    private lowerExpr(expr: Expr) {
         switch (expr.kind.type) {
-            case "string":
             case "error":
                 break;
+            case "sym":
+                return this.lowerSymExpr(expr);
+            case "null":
+                break;
             case "int":
-                return this.lowerInt(expr);
+                return this.lowerIntExpr(expr);
+            case "bool":
+                break;
+            case "string":
+                return this.lowerStringExpr(expr);
             case "ident":
+                break;
             case "group":
+                break;
             case "field":
+                break;
             case "index":
+                break;
             case "call":
+                return this.lowerCallExpr(expr);
             case "unary":
                 break;
             case "binary":
                 return this.lowerBinaryExpr(expr);
             case "if":
-            case "bool":
-            case "null":
+                return this.lowerIfExpr(expr);
             case "loop":
-            case "block":
                 break;
-            case "sym":
-                return this.lowerSym(expr);
+            case "block":
+                return this.lowerBlockExpr(expr);
         }
-        throw new Error(`Unhandled expr ${expr.kind.type}`);
+        throw new Error(`unhandled expr '${expr.kind.type}'`);
     }
 
-    lowerInt(expr: Expr) {
-        if (expr.kind.type !== "int") {
-            throw new Error();
-        }
-        this.program.push(Ops.PushInt);
-        this.program.push(expr.kind.value);
-    }
-
-    lowerSym(expr: Expr) {
+    private lowerSymExpr(expr: Expr) {
         if (expr.kind.type !== "sym") {
             throw new Error();
         }
-        if (expr.kind.defType == "let") {
-            this.program.push(Ops.LoadLocal);
-            this.program.push(this.locals.symId(expr.kind.ident));
+        if (expr.kind.sym.type === "let") {
+            this.program.push(
+                Ops.LoadLocal,
+                this.locals.symId(expr.kind.ident),
+            );
             return;
         }
-        throw new Error(`Unhandled sym deftype ${expr.kind.defType}`);
+        if (expr.kind.sym.type === "fn_param") {
+            this.program.push(
+                Ops.LoadLocal,
+                this.locals.symId(expr.kind.ident),
+            );
+            return;
+        }
+        if (expr.kind.sym.type === "fn") {
+            const addr = this.fnStmtIdAddrMap[expr.kind.sym.stmt.id];
+            this.program.push(Ops.PushPtr, addr);
+            return;
+        }
+        throw new Error(`unhandled sym type '${expr.kind.sym.type}'`);
     }
 
-    lowerBinaryExpr(expr: Expr) {
+    private lowerIntExpr(expr: Expr) {
+        if (expr.kind.type !== "int") {
+            throw new Error();
+        }
+        this.program.push(Ops.PushInt, expr.kind.value);
+    }
+
+    private lowerStringExpr(expr: Expr) {
+        if (expr.kind.type !== "string") {
+            throw new Error();
+        }
+        this.program.push(Ops.PushString);
+        for (let i = 0; i < expr.kind.value.length; ++i) {
+            this.program.push(expr.kind.value.charCodeAt(i));
+        }
+    }
+
+    private lowerBinaryExpr(expr: Expr) {
         if (expr.kind.type !== "binary") {
             throw new Error();
         }
@@ -171,10 +194,57 @@ export class Lowerer {
                 case "and":
             }
         }
+        if (expr.vtype!.type === "string") {
+            if (expr.kind.binaryType === "+") {
+                this.program.push(Ops.Builtin, Builtins.StringAdd);
+                return;
+            }
+        }
         throw new Error(
-            `Unhandled vtype/binaryType '${
-                expr.vtype!.type
-            }/${expr.kind.binaryType}'`,
+            `unhandled binaryType` +
+                ` '${vtypeToString(expr.kind.left.vtype!)}'` +
+                ` ${expr.kind.binaryType}` +
+                ` '${vtypeToString(expr.kind.left.vtype!)}'`,
         );
     }
+
+    private lowerCallExpr(expr: Expr) {
+        if (expr.kind.type !== "call") {
+            throw new Error();
+        }
+        for (const arg of expr.kind.args) {
+            this.lowerExpr(arg);
+        }
+        this.lowerExpr(expr.kind.subject);
+    }
+
+    private lowerIfExpr(expr: Expr) {
+        if (expr.kind.type !== "if") {
+            throw new Error();
+        }
+        this.lowerExpr(expr.kind.cond);
+        this.lowerExpr(expr.kind.truthy);
+        const falsyIndex = this.program.length;
+        if (expr.kind.falsy) {
+            this.lowerExpr(expr.kind.falsy);
+        }
+        const doneIndex = this.program.length;
+    }
+
+    private lowerBlockExpr(expr: Expr) {
+        if (expr.kind.type !== "block") {
+            throw new Error();
+        }
+        const outerLocals = this.locals;
+        this.locals = new LocalLeaf(this.locals);
+        for (const stmt of expr.kind.stmts) {
+            this.lowerStmt(stmt);
+        }
+        if (expr.kind.expr) {
+            this.lowerExpr(expr.kind.expr);
+        } else {
+            this.program.push(Ops.PushNull);
+        }
+        this.locals = outerLocals;
+    }
 }
diff --git a/compiler/Resolver.ts b/compiler/Resolver.ts
index 5442f09..106bac5 100644
--- a/compiler/Resolver.ts
+++ b/compiler/Resolver.ts
@@ -1,42 +1,43 @@
-import { Expr, Stmt, Sym } from "./ast.ts";
+import { Expr, Stmt } from "./ast.ts";
+import {
+    FnSyms,
+    GlobalSyms,
+    LeafSyms,
+    StaticSyms,
+    Syms,
+} from "./resolver_syms.ts";
 import { Pos } from "./Token.ts";
 
-type SymMap = { [ident: string]: Sym };
-
-class Syms {
-    private syms: SymMap = {};
-
-    public constructor(private parent?: Syms) {}
-
-    public define(ident: string, sym: Sym) {
-        this.syms[ident] = sym;
-    }
-
-    public definedLocally(ident: string): boolean {
-        return ident in this.syms;
-    }
-
-    public get(ident: string): { ok: true; sym: Sym } | { ok: false } {
-        if (ident in this.syms) {
-            return { ok: true, sym: this.syms[ident] };
-        }
-        if (this.parent) {
-            return this.parent.get(ident);
-        }
-        return { ok: false };
-    }
-}
-
 export class Resolver {
-    private root = new Syms();
+    private root = new GlobalSyms();
 
     public resolve(stmts: Stmt[]) {
-        const scopeSyms = new Syms(this.root);
+        const scopeSyms = new StaticSyms(this.root);
+        this.scoutFnStmts(stmts, scopeSyms);
         for (const stmt of stmts) {
             this.resolveStmt(stmt, scopeSyms);
         }
     }
 
+    private scoutFnStmts(stmts: Stmt[], syms: Syms) {
+        for (const stmt of stmts) {
+            if (stmt.kind.type !== "fn") {
+                continue;
+            }
+            if (syms.definedLocally(stmt.kind.ident)) {
+                this.reportAlreadyDefined(stmt.kind.ident, stmt.pos, syms);
+                return;
+            }
+            const ident = stmt.kind.ident;
+            syms.define(ident, {
+                ident: stmt.kind.ident,
+                type: "fn",
+                pos: stmt.pos,
+                stmt,
+            });
+        }
+    }
+
     private resolveExpr(expr: Expr, syms: Syms) {
         if (expr.kind.type === "error") {
             return;
@@ -51,7 +52,8 @@ export class Resolver {
             return;
         }
         if (expr.kind.type === "block") {
-            const childSyms = new Syms(syms);
+            const childSyms = new LeafSyms(syms);
+            this.scoutFnStmts(expr.kind.stmts, childSyms);
             for (const stmt of expr.kind.stmts) {
                 this.resolveStmt(stmt, childSyms);
             }
@@ -119,14 +121,8 @@ export class Resolver {
         expr.kind = {
             type: "sym",
             ident: ident.value,
-            defType: sym.type,
+            sym,
         };
-        if (sym.stmt) {
-            expr.kind.stmt = sym.stmt;
-        }
-        if (sym.param) {
-            expr.kind.param = sym.param;
-        }
     }
 
     private resolveStmt(stmt: Stmt, syms: Syms) {
@@ -187,18 +183,7 @@ export class Resolver {
         if (stmt.kind.type !== "fn") {
             throw new Error("expected fn statement");
         }
-        if (syms.definedLocally(stmt.kind.ident)) {
-            this.reportAlreadyDefined(stmt.kind.ident, stmt.pos, syms);
-            return;
-        }
-        const ident = stmt.kind.ident;
-        syms.define(ident, {
-            ident: stmt.kind.ident,
-            type: "fn",
-            pos: stmt.pos,
-            stmt,
-        });
-        const fnScopeSyms = new Syms(syms);
+        const fnScopeSyms = new FnSyms(syms);
         for (const param of stmt.kind.params) {
             if (fnScopeSyms.definedLocally(param.ident)) {
                 this.reportAlreadyDefined(param.ident, param.pos, syms);
@@ -214,7 +199,7 @@ export class Resolver {
         this.resolveExpr(stmt.kind.body, fnScopeSyms);
     }
 
-    private reportUseOfUndefined(ident: string, pos: Pos, syms: Syms) {
+    private reportUseOfUndefined(ident: string, pos: Pos, _syms: Syms) {
         console.error(
             `use of undefined symbol '${ident}' at ${pos.line}${pos.col}`,
         );
diff --git a/compiler/arch.ts b/compiler/arch.ts
index 851e67a..ba900a9 100644
--- a/compiler/arch.ts
+++ b/compiler/arch.ts
@@ -30,4 +30,13 @@ export const Ops = {
     Xor: 22,
     Not: 23,
     SourceMap: 24,
+    Builtin: 25,
+    ReserveStatics: 26,
+    LoadStatic: 27,
+    StoreStatic: 28,
+} as const;
+
+export type Builtins = typeof Builtins;
+export const Builtins = {
+    StringAdd: 0,
 } as const;
diff --git a/compiler/ast.ts b/compiler/ast.ts
index 05255f9..89b1ef8 100644
--- a/compiler/ast.ts
+++ b/compiler/ast.ts
@@ -71,18 +71,21 @@ export type ExprKind =
     | {
         type: "sym";
         ident: string;
-        defType: "let" | "fn" | "fn_param" | "builtin";
-        stmt?: Stmt;
-        param?: Param;
+        sym: Sym;
     };
 
 export type Sym = {
     ident: string;
-    type: "let" | "fn" | "fn_param" | "builtin";
     pos?: Pos;
-    stmt?: Stmt;
-    param?: Param;
-};
+} & SymKind;
+
+export type SymKind =
+    | { type: "let"; stmt: Stmt; param: Param }
+    | { type: "let_static"; stmt: Stmt; param: Param }
+    | { type: "fn"; stmt: Stmt }
+    | { type: "fn_param"; param: Param }
+    | { type: "closure"; inner: Sym }
+    | { type: "builtin" };
 
 export type EType = {
     kind: ETypeKind;
diff --git a/compiler/example-no-types.slg b/compiler/example-no-types.slg
deleted file mode 100644
index b1bd82b..0000000
--- a/compiler/example-no-types.slg
+++ /dev/null
@@ -1,29 +0,0 @@
-
-fn sum(a, b) {
-    + a b;
-}
-
-sum(2,3); // -> 5
-
-let a = "Hello";
- 
-let b = "world";
-
-println(+ + + a " " b "!"); // -> "Hello world!"
-
-if == a b {
-    println("whaaaat");
-}
-else {
-    println(":o");
-}
-
-loop {
-    let i = 0;
-
-    if >= i 10 {
-       break;
-    }
-
-    i = + i 1;
-}
\ No newline at end of file
diff --git a/compiler/example.slg b/compiler/example.slg
index aa9fd79..f502665 100755
--- a/compiler/example.slg
+++ b/compiler/example.slg
@@ -6,27 +6,29 @@ fn sum(a: int, b: int) -> int {
     + a b
 }
 
-sum(2,3); // -> 5
+fn main() {
+    sum(2,3); // -> 5
 
-let a: string = "Hello";
- 
-let b = "world";
+    let a: string = "Hello";
+     
+    let b = "world";
 
-println(+ + + a " " b "!"); // -> "Hello world!"
+    println(+ + + a " " b "!"); // -> "Hello world!"
 
-if == a b {
-    println("whaaaat");
-}
-else {
-    println(":o");
-}
-
-loop {
-    let i = 0;
-
-    if >= i 10 {
-       break;
+    if == a b {
+        println("whaaaat");
+    }
+    else {
+        println(":o");
     }
 
-    i = + i 1;
-}
\ No newline at end of file
+    loop {
+        let i = 0;
+
+        if >= i 10 {
+           break;
+        }
+
+        i = + i 1;
+    }
+}
diff --git a/compiler/lowerer_locals.ts b/compiler/lowerer_locals.ts
new file mode 100644
index 0000000..2d43d5c
--- /dev/null
+++ b/compiler/lowerer_locals.ts
@@ -0,0 +1,59 @@
+export interface Locals {
+    reserveId(id: number): void;
+    allocSym(ident: string): void;
+    symId(ident: string): number;
+}
+
+export class LocalsFnRoot implements Locals {
+    private localsAmount = 0;
+    private localIdCounter = 0;
+    private symLocalMap: { [key: string]: number } = {};
+
+    constructor(private parent?: Locals) {
+    }
+
+    public reserveId(id: number): void {
+        this.localsAmount = Math.max(id + 1, this.localsAmount);
+    }
+
+    public allocSym(ident: string) {
+        this.symLocalMap[ident] = this.localIdCounter;
+        this.localIdCounter++;
+        this.reserveId(this.localIdCounter);
+    }
+
+    public symId(ident: string): number {
+        if (ident in this.symLocalMap) {
+            return this.symLocalMap[ident];
+        }
+        if (this.parent) {
+            return this.parent.symId(ident);
+        }
+        throw new Error(`undefined symbol '${ident}'`);
+    }
+}
+
+export class LocalLeaf implements Locals {
+    private localIdCounter = 0;
+    private symLocalMap: { [key: string]: number } = {};
+
+    constructor(private parent: Locals) {
+    }
+
+    public reserveId(id: number): void {
+        this.parent.reserveId(id);
+    }
+
+    public allocSym(ident: string) {
+        this.symLocalMap[ident] = this.localIdCounter;
+        this.localIdCounter++;
+        this.reserveId(this.localIdCounter);
+    }
+
+    public symId(ident: string): number {
+        if (ident in this.symLocalMap) {
+            return this.symLocalMap[ident];
+        }
+        return this.parent.symId(ident);
+    }
+}
diff --git a/compiler/main.ts b/compiler/main.ts
index 81b2f42..ac550c8 100644
--- a/compiler/main.ts
+++ b/compiler/main.ts
@@ -1,21 +1,19 @@
 import { Checker } from "./Checker.ts";
 import { Lexer } from "./Lexer.ts";
+import { Lowerer } from "./Lowerer.ts";
 import { Parser } from "./Parser.ts";
 import { Resolver } from "./Resolver.ts";
 
 const text = await Deno.readTextFile("example.slg");
-// const text = await Deno.readTextFile("example.slg");
 
 const lexer = new Lexer(text);
 
-// while (token !== null) {
-//     const value = token.identValue ?? token.intValue ?? token.stringValue ?? "";
-//     console.log(`${token.type}\t${value}`)
-//     token = lexer.next();
-// }
-
 const parser = new Parser(lexer);
 const ast = parser.parseStmts();
 new Resolver().resolve(ast);
 new Checker().check(ast);
 // console.log(JSON.stringify(ast, null, 4))
+const lowerer = new Lowerer();
+lowerer.lower(ast);
+const program = lowerer.finish();
+console.log(JSON.stringify(program, null, 4));
diff --git a/compiler/resolver_syms.ts b/compiler/resolver_syms.ts
new file mode 100644
index 0000000..ce976ef
--- /dev/null
+++ b/compiler/resolver_syms.ts
@@ -0,0 +1,115 @@
+import { Sym } from "./ast.ts";
+
+export type SymMap = { [ident: string]: Sym };
+
+export interface Syms {
+    define(ident: string, sym: Sym): void;
+    definedLocally(ident: string): boolean;
+    get(ident: string): { ok: true; sym: Sym } | { ok: false };
+}
+
+export class GlobalSyms implements Syms {
+    private syms: SymMap = {};
+
+    public constructor() {}
+
+    public define(ident: string, sym: Sym) {
+        if (sym.type === "let") {
+            this.define(ident, {
+                ...sym,
+                type: "let_static",
+            });
+            return;
+        }
+        this.syms[ident] = sym;
+    }
+
+    public definedLocally(ident: string): boolean {
+        return ident in this.syms;
+    }
+
+    public get(ident: string): { ok: true; sym: Sym } | { ok: false } {
+        if (ident in this.syms) {
+            return { ok: true, sym: this.syms[ident] };
+        }
+        return { ok: false };
+    }
+}
+
+export class StaticSyms implements Syms {
+    private syms: SymMap = {};
+
+    public constructor(private parent: GlobalSyms) {}
+
+    public define(ident: string, sym: Sym) {
+        if (sym.type === "let") {
+            this.define(ident, {
+                ...sym,
+                type: "let_static",
+            });
+            return;
+        }
+        this.syms[ident] = sym;
+    }
+
+    public definedLocally(ident: string): boolean {
+        return ident in this.syms;
+    }
+
+    public get(ident: string): { ok: true; sym: Sym } | { ok: false } {
+        if (ident in this.syms) {
+            return { ok: true, sym: this.syms[ident] };
+        }
+        return this.parent.get(ident);
+    }
+}
+
+export class FnSyms implements Syms {
+    private syms: SymMap = {};
+
+    public constructor(private parent: Syms) {}
+
+    public define(ident: string, sym: Sym) {
+        if (sym.type === "let") {
+            this.define(ident, {
+                ...sym,
+                type: "closure",
+                inner: sym,
+            });
+            return;
+        }
+        this.syms[ident] = sym;
+    }
+
+    public definedLocally(ident: string): boolean {
+        return ident in this.syms;
+    }
+
+    public get(ident: string): { ok: true; sym: Sym } | { ok: false } {
+        if (ident in this.syms) {
+            return { ok: true, sym: this.syms[ident] };
+        }
+        return this.parent.get(ident);
+    }
+}
+
+export class LeafSyms implements Syms {
+    private syms: SymMap = {};
+
+    public constructor(private parent: Syms) {}
+
+    public define(ident: string, sym: Sym) {
+        this.syms[ident] = sym;
+    }
+
+    public definedLocally(ident: string): boolean {
+        return ident in this.syms;
+    }
+
+    public get(ident: string): { ok: true; sym: Sym } | { ok: false } {
+        if (ident in this.syms) {
+            return { ok: true, sym: this.syms[ident] };
+        }
+        return this.parent.get(ident);
+    }
+}