diff --git a/src/AstGen.zig b/src/AstGen.zig
index 2171aea..1326f01 100644
--- a/src/AstGen.zig
+++ b/src/AstGen.zig
@@ -18,21 +18,8 @@ errors: std.ArrayListUnmanaged(Ast.Error) = .empty,
 pub const InnerError = error{
     OutOfMemory,
     SemanticError,
-    TooManyConstants,
     InvalidCharacter,
-} || anyerror;
-
-pub const Fixup = struct {
-    mode: enum {
-        relative,
-        absolute,
-    },
-    label_index: usize,
-    code_offset: usize,
-};
-
-pub const Label = struct {
-    code_offset: usize,
+    Overflow,
 };
 
 const Scope = struct {
@@ -73,8 +60,20 @@ const GenIr = struct {
     instructions: *std.ArrayListUnmanaged(Ir.Inst.Index),
     instructions_top: usize,
 
-    pub fn unstack(gi: *GenIr) void {
-        gi.instructions.items.len = gi.instructions_top;
+    const unstacked_top = std.math.maxInt(usize);
+
+    pub fn unstack(self: *GenIr) void {
+        if (self.instructions_top != unstacked_top) {
+            self.instructions.items.len = self.instructions_top;
+            self.instructions_top = unstacked_top;
+        }
+    }
+
+    fn instructionsSlice(self: *const GenIr) []Ir.Inst.Index {
+        return if (self.instructions_top == unstacked_top)
+            &[0]Ir.Inst.Index{}
+        else
+            self.instructions.items[self.instructions_top..];
     }
 
     fn fail(
@@ -85,25 +84,14 @@ const GenIr = struct {
         return self.astgen.fail(tag, node);
     }
 
-    fn instructionsSlice(gi: *const GenIr) []Ir.Inst.Index {
-        return gi.instructions.items[gi.instructions_top..];
-    }
-
     pub fn makeSubBlock(self: *GenIr) GenIr {
         return .{
             .astgen = self.astgen,
             .instructions = self.instructions,
-            .instructions_top = self.astgen.instructions.items.len,
+            .instructions_top = self.instructions.items.len,
         };
     }
 
-    pub fn addGlobal(self: *GenIr, decl: Decl) error{OutOfMemory}!void {
-        const gpa = self.astgen.gpa;
-        try self.astgen.globals.append(gpa, .{
-            .variable = .{ .name = decl.string_index },
-        });
-    }
-
     pub fn add(gi: *GenIr, inst: Ir.Inst) !Ir.Inst.Index {
         const gpa = gi.astgen.gpa;
         try gi.instructions.ensureUnusedCapacity(gpa, 1);
@@ -152,6 +140,15 @@ const GenIr = struct {
         });
     }
 
+    pub fn addDeclRef(gi: *GenIr, decl_ref: Ir.NullTerminatedString) !Ir.Inst.Index {
+        return add(gi, .{
+            .tag = .decl_ref,
+            .data = .{ .string = .{
+                .start = decl_ref,
+            } },
+        });
+    }
+
     pub fn makePayloadNode(gi: *GenIr, tag: Ir.Inst.Tag) !Ir.Inst.Index {
         const gpa = gi.astgen.gpa;
         const inst_index: Ir.Inst.Index = @enumFromInt(gi.astgen.instructions.items.len);
@@ -164,41 +161,70 @@ const GenIr = struct {
         return inst_index;
     }
 
-    pub fn makeDeclNode(gi: *GenIr) !Ir.Inst.Index {
-        return makePayloadNode(gi, .decl_knot);
+    pub fn makeDeclaration(gi: *GenIr) !Ir.Inst.Index {
+        return makePayloadNode(gi, .declaration);
     }
 
     pub fn makeBlockInst(gi: *GenIr) !Ir.Inst.Index {
         return makePayloadNode(gi, .block);
     }
 
-    pub fn setDecl(
-        gi: *GenIr,
-        inst: Ir.Inst.Index,
-        name_ref: Ir.NullTerminatedString,
-    ) !void {
+    pub fn addKnot(gi: *GenIr) !Ir.Inst.Index {
         const astgen = gi.astgen;
         const gpa = astgen.gpa;
         const body = gi.instructionsSlice();
         const extra_len = @typeInfo(Ir.Inst.Knot).@"struct".fields.len + body.len;
         try astgen.extra.ensureUnusedCapacity(gpa, extra_len);
 
-        const inst_data = &astgen.instructions.items[@intFromEnum(inst)].data;
+        const knot_node = try makePayloadNode(gi, .decl_knot);
+        const inst_data = &astgen.instructions.items[@intFromEnum(knot_node)].data;
         inst_data.payload.payload_index = astgen.addExtraAssumeCapacity(
-            Ir.Inst.Knot{ .name_ref = name_ref, .body_len = @intCast(body.len) },
+            Ir.Inst.Knot{ .body_len = @intCast(body.len) },
         );
 
         for (body) |inst_index| {
             astgen.extra.appendAssumeCapacity(@intFromEnum(inst_index));
         }
-        gi.unstack();
+        return knot_node;
+    }
+
+    pub fn addVar(gi: *GenIr) !Ir.Inst.Index {
+        const astgen = gi.astgen;
+        const gpa = astgen.gpa;
+        const new_index: Ir.Inst.Index = @enumFromInt(astgen.instructions.items.len);
+
+        try astgen.instructions.ensureUnusedCapacity(gpa, 1);
+        try gi.instructions.ensureUnusedCapacity(gpa, 1);
+
+        gi.astgen.instructions.appendAssumeCapacity(.{
+            .tag = .decl_var,
+            .data = .{
+                .payload = .{ .payload_index = undefined },
+            },
+        });
+
+        const body = gi.instructionsSlice();
+        const extra_len = @typeInfo(Ir.Inst.Var).@"struct".fields.len + body.len;
+        try astgen.extra.ensureUnusedCapacity(gpa, extra_len);
+
+        const inst_data = &astgen.instructions.items[@intFromEnum(new_index)].data;
+        inst_data.payload.payload_index = astgen.addExtraAssumeCapacity(
+            Ir.Inst.Var{ .body_len = @intCast(body.len) },
+        );
+
+        for (body) |inst_index| {
+            astgen.extra.appendAssumeCapacity(@intFromEnum(inst_index));
+        }
+
+        gi.instructions.appendAssumeCapacity(new_index);
+        return new_index;
     }
 
     pub fn setBlockBody(gi: *GenIr, inst: Ir.Inst.Index) !void {
         const astgen = gi.astgen;
         const gpa = astgen.gpa;
         const body = gi.instructionsSlice();
-        const extra_len = @typeInfo(Ir.Inst.Knot).@"struct".fields.len + body.len;
+        const extra_len = @typeInfo(Ir.Inst.Block).@"struct".fields.len + body.len;
         try astgen.extra.ensureUnusedCapacity(gpa, extra_len);
 
         const inst_data = &astgen.instructions.items[@intFromEnum(inst)].data;
@@ -220,6 +246,27 @@ pub fn deinit(astgen: *AstGen) void {
     astgen.errors.deinit(gpa);
 }
 
+fn setDeclaration(
+    decl_index: Ir.Inst.Index,
+    args: struct {
+        name: Ir.NullTerminatedString,
+        ref: Ir.Inst.Index,
+        body_gi: *GenIr,
+    },
+) !void {
+    const astgen = args.body_gi.astgen;
+    const gpa = astgen.gpa;
+    const extra_len = @typeInfo(Ir.Inst.Declaration).@"struct".fields.len;
+    try astgen.extra.ensureUnusedCapacity(gpa, extra_len);
+
+    const inst_data = &astgen.instructions.items[@intFromEnum(decl_index)].data;
+    inst_data.payload.payload_index = astgen.addExtraAssumeCapacity(
+        Ir.Inst.Declaration{ .name = args.name, .value = args.ref },
+    );
+
+    args.body_gi.unstack();
+}
+
 fn addExtraAssumeCapacity(astgen: *AstGen, extra: anytype) u32 {
     const fields = std.meta.fields(@TypeOf(extra));
     const extra_index: u32 = @intCast(astgen.extra.items.len);
@@ -280,7 +327,7 @@ fn stringFromBytes(astgen: *AstGen, bytes: []const u8) error{OutOfMemory}!Ir.Nul
     });
     if (gop.found_existing) {
         string_bytes.shrinkRetainingCapacity(str_index);
-        return @enumFromInt(str_index);
+        return @enumFromInt(gop.key_ptr.*);
     } else {
         gop.key_ptr.* = str_index;
         try string_bytes.append(gpa, 0);
@@ -346,17 +393,11 @@ fn logicalOp(
 }
 
 fn trueLiteral(gi: *GenIr) InnerError!Ir.Inst.Index {
-    return gi.add(.{
-        .tag = .true_literal,
-        .data = undefined,
-    });
+    return gi.add(.{ .tag = .true_literal, .data = undefined });
 }
 
 fn falseLiteral(gi: *GenIr) InnerError!Ir.Inst.Index {
-    return gi.add(.{
-        .tag = .false_literal,
-        .data = undefined,
-    });
+    return gi.add(.{ .tag = .false_literal, .data = undefined });
 }
 
 fn numberLiteral(gen: *GenIr, node: *const Ast.Node) InnerError!Ir.Inst.Index {
@@ -382,10 +423,10 @@ fn stringExpr(gen: *GenIr, expr_node: *const Ast.Node) InnerError!Ir.Inst.Index
     return stringLiteral(gen, first_node);
 }
 
-fn identifier(gen: *GenIr, scope: *Scope, node: *const Ast.Node) InnerError!Ir.Inst.Index {
-    const name_ref = try gen.astgen.stringFromNode(node);
-    if (scope.lookup(name_ref)) |_| {}
-    return gen.fail(.unknown_identifier, node);
+fn identifier(gen: *GenIr, _: *Scope, node: *const Ast.Node) InnerError!Ir.Inst.Index {
+    const name_str = try gen.astgen.stringFromNode(node);
+    return gen.addDeclRef(name_str);
+    //return gen.fail(.unknown_identifier, node);
 }
 
 fn expr(gen: *GenIr, scope: *Scope, optional_expr: ?*const Ast.Node) InnerError!Ir.Inst.Index {
@@ -795,48 +836,33 @@ fn choiceStmt(gen: *GenIr, scope: *Scope, stmt_node: *const Ast.Node) InnerError
     }
 }
 
-fn varDecl(gen: *GenIr, scope: *Scope, decl_node: *const Ast.Node) !void {
-    const identifier_node = decl_node.data.bin.lhs orelse unreachable;
-    const expr_node = decl_node.data.bin.rhs orelse unreachable;
-    const name_ref = try gen.astgen.stringFromNode(identifier_node);
-    const decl_symbol: Decl = blk: switch (decl_node.tag) {
-        .temp_decl => {
-            const stack_slot = try gen.makeStackSlot();
-            break :blk .{
-                .local = .{
-                    .decl_node = decl_node,
-                    .stack_slot = stack_slot,
-                },
-            };
-        },
-        .var_decl, .const_decl => |tag| {
-            const constant_slot = try gen.makeConstant(.{
-                .string = name_ref,
-            });
-            break :blk .{
-                .global = .{
-                    .decl_node = decl_node,
-                    .is_constant = tag == .const_decl,
-                    .constant_slot = constant_slot,
-                },
-            };
-        },
-        else => unreachable,
-    };
+fn varDecl(gi: *GenIr, scope: *Scope, decl_node: *const Ast.Node) !void {
+    const gpa = gi.astgen.gpa;
+    const identifier_node = decl_node.data.bin.lhs.?;
+    const expr_node = decl_node.data.bin.rhs.?;
+    const name_ref = try gi.astgen.stringFromNode(identifier_node);
 
-    try scope.insert(name_ref, decl_symbol);
-    try expr(gen, scope, expr_node);
-
-    switch (decl_symbol) {
-        .local => |data| {
-            try gen.emitConstInst(.store, data.stack_slot);
-        },
-        .global => |data| {
-            try gen.emitConstInst(.store_global, data.constant_slot);
-        },
-        else => unreachable,
+    if (scope.lookup(name_ref)) |_| {
+        return gi.fail(.redefined_identifier, decl_node);
     }
-    try gen.emitSimpleInst(.pop);
+
+    const decl_inst = try gi.makeDeclaration();
+    try gi.instructions.append(gpa, decl_inst);
+
+    var decl_block = gi.makeSubBlock();
+    defer decl_block.unstack();
+
+    _ = try expr(&decl_block, scope, expr_node);
+    try scope.insert(name_ref, .{
+        .decl_node = decl_node,
+    });
+
+    const var_inst = try decl_block.addVar();
+    try setDeclaration(decl_inst, .{
+        .name = name_ref,
+        .ref = var_inst,
+        .body_gi = &decl_block,
+    });
 }
 
 fn blockInner(gi: *GenIr, parent_scope: *Scope, stmt_list: []*Ast.Node) !void {
@@ -845,8 +871,8 @@ fn blockInner(gi: *GenIr, parent_scope: *Scope, stmt_list: []*Ast.Node) !void {
 
     for (stmt_list) |inner_node| {
         _ = switch (inner_node.tag) {
-            //.var_decl => try varDecl(gen, scope, inner_node),
-            //.const_decl => try varDecl(gen, scope, inner_node),
+            .var_decl => try varDecl(gi, &child_scope, inner_node),
+            .const_decl => try varDecl(gi, &child_scope, inner_node),
             //.temp_decl => try varDecl(gen, scope, inner_node),
             //.assign_stmt => try assignStmt(gen, scope, inner_node),
             .content_stmt => try contentStmt(gi, &child_scope, inner_node),
@@ -884,7 +910,7 @@ fn defaultBlock(
 ) InnerError!void {
     const astgen = gi.astgen;
     const gpa = astgen.gpa;
-    const decl_inst = try gi.makeDeclNode();
+    const decl_inst = try gi.makeDeclaration();
     try gi.instructions.append(gpa, decl_inst);
 
     var decl_scope = gi.makeSubBlock();
@@ -894,9 +920,12 @@ fn defaultBlock(
     const block_stmts = body_node.data.list.items orelse unreachable;
     try blockInner(&decl_scope, scope, block_stmts);
 
-    std.debug.print("{any}\n", .{decl_scope});
-    const name_ref = try decl_scope.astgen.stringFromBytes("$__main__$");
-    try decl_scope.setDecl(decl_inst, name_ref);
+    const knot_inst = try decl_scope.addKnot();
+    try setDeclaration(decl_inst, .{
+        .name = try astgen.stringFromBytes("$__main__$"),
+        .ref = knot_inst,
+        .body_gi = &decl_scope,
+    });
 }
 
 fn stitchDecl(_: *GenIr, _: *Scope, _: *const Ast.Node) InnerError!void {}
@@ -932,18 +961,16 @@ fn knotDecl(gen: *GenIr, scope: *Scope, decl_node: *const Ast.Node) InnerError!v
 fn file(root_gi: *GenIr, scope: *Scope, file_node: *const Ast.Node) InnerError!void {
     const astgen = root_gi.astgen;
     const gpa = astgen.gpa;
-
     const file_inst = try root_gi.makePayloadNode(.file);
     try root_gi.instructions.append(gpa, file_inst);
 
+    var start_index: usize = 0;
     var file_scope = root_gi.makeSubBlock();
     defer file_scope.unstack();
     // TODO: Make sure this is non-nullable.
     const nested_decls_list = file_node.data.list.items orelse return;
     if (nested_decls_list.len == 0) return;
 
-    var start_index: usize = 0;
-
     const first_child = nested_decls_list[0];
     if (first_child.tag == .block_stmt) {
         try defaultBlock(&file_scope, scope, first_child);
@@ -975,7 +1002,7 @@ pub fn generate(gpa: std.mem.Allocator, tree: *const Ast) !Ir {
     };
     defer astgen.deinit();
 
-    // First entry is reserved for the empty string sentinel.
+    // First entry is reserved for Ir.NullTerminatedString.empty.
     try astgen.string_bytes.append(gpa, 0);
 
     var instructions: std.ArrayListUnmanaged(Ir.Inst.Index) = .empty;
diff --git a/src/Ir.zig b/src/Ir.zig
index 69cf5ff..2a41afb 100644
--- a/src/Ir.zig
+++ b/src/Ir.zig
@@ -18,7 +18,10 @@ pub const Inst = struct {
 
     pub const Tag = enum {
         file,
+        declaration,
         decl_knot,
+        decl_var,
+        decl_ref,
         block,
         add,
         sub,
@@ -57,8 +60,16 @@ pub const Inst = struct {
         },
     };
 
+    pub const Declaration = struct {
+        name: NullTerminatedString,
+        value: Inst.Index,
+    };
+
     pub const Knot = struct {
-        name_ref: NullTerminatedString,
+        body_len: u32,
+    };
+
+    pub const Var = struct {
         body_len: u32,
     };
 
@@ -151,12 +162,22 @@ const Render = struct {
         try io_w.writeAll(")");
     }
 
-    fn renderKnotInst(r: *Render, ir: Ir, inst: Inst) Error!void {
+    fn renderKnotDecl(r: *Render, ir: Ir, inst: Inst) Error!void {
         const io_w = r.writer;
         const extra = ir.extraData(Inst.Knot, inst.data.payload.payload_index);
         const body_slice = ir.bodySlice(extra.end, extra.data.body_len);
-        const knot_ident_str = ir.nullTerminatedString(extra.data.name_ref);
-        try io_w.print("{s}(name=\"{s}\",body=", .{ @tagName(inst.tag), knot_ident_str });
+
+        try io_w.print("{s}(body=", .{@tagName(inst.tag)});
+        try renderBodyInner(r, ir, body_slice);
+        try io_w.writeAll(")");
+    }
+
+    fn renderVarDecl(r: *Render, ir: Ir, inst: Inst) Error!void {
+        const io_w = r.writer;
+        const extra = ir.extraData(Inst.Knot, inst.data.payload.payload_index);
+        const body_slice = ir.bodySlice(extra.end, extra.data.body_len);
+
+        try io_w.print("{s}(body=", .{@tagName(inst.tag)});
         try renderBodyInner(r, ir, body_slice);
         try io_w.writeAll(")");
     }
@@ -171,6 +192,21 @@ const Render = struct {
         return io_w.writeAll(")");
     }
 
+    fn renderDeclaration(r: *Render, ir: Ir, inst: Inst) Error!void {
+        const io_w = r.writer;
+        const extra = ir.extraData(Inst.Declaration, inst.data.payload.payload_index);
+        const ident_str = ir.nullTerminatedString(extra.data.name);
+
+        try io_w.print("{s}(name=\"{s}\", value={{\n", .{ @tagName(inst.tag), ident_str });
+        {
+            const old_len = try r.prefix.pushChildPrefix(r.gpa);
+            defer r.prefix.restore(old_len);
+            try renderInst(r, ir, extra.data.value);
+        }
+        try r.prefix.writeIndent(io_w);
+        return io_w.writeAll(")");
+    }
+
     fn renderInst(r: *Render, ir: Ir, index: Inst.Index) Error!void {
         const io_w = r.writer;
         const inst_index: u32 = @intFromEnum(index);
@@ -180,7 +216,13 @@ const Render = struct {
         try io_w.print("%{d} = ", .{inst_index});
         switch (inst.tag) {
             .file => try r.renderFileInst(ir, inst),
-            .decl_knot => try r.renderKnotInst(ir, inst),
+            .declaration => try r.renderDeclaration(ir, inst),
+            .decl_knot => try r.renderKnotDecl(ir, inst),
+            .decl_var => try r.renderVarDecl(ir, inst),
+            .decl_ref => {
+                const str_bytes = inst.data.string.get(ir);
+                try io_w.print("{s}(\"{s}\")", .{ @tagName(inst.tag), str_bytes });
+            },
             .block => try r.renderBlockInst(ir, inst),
             .add => try r.renderBinaryInst(inst),
             .sub => try r.renderBinaryInst(inst),
diff --git a/src/Sema.zig b/src/Sema.zig
new file mode 100644
index 0000000..f47919b
--- /dev/null
+++ b/src/Sema.zig
@@ -0,0 +1,261 @@
+const std = @import("std");
+const Ir = @import("Ir.zig");
+const Story = @import("Story.zig");
+const Object = Story.Object;
+const Sema = @This();
+
+gpa: std.mem.Allocator,
+ir: *const Ir,
+bytecode: std.ArrayListUnmanaged(u8) = .empty,
+constants: std.ArrayListUnmanaged(CompiledStory.Constant) = .empty,
+knots: std.ArrayListUnmanaged(CompiledStory.Knot) = .empty,
+
+const InnerError = error{
+    OutOfMemory,
+    TooManyConstants,
+};
+
+fn deinit(sema: *Sema) void {
+    const gpa = sema.gpa;
+    sema.bytecode.deinit(gpa);
+    sema.constants.deinit(gpa);
+    sema.knots.deinit(gpa);
+    sema.* = undefined;
+}
+
+fn resolveIndex(sema: *Sema, index: Ir.Inst.Index) Ir.Inst {
+    return sema.ir.instructions[@intFromEnum(index)];
+}
+
+fn emitByte(sema: *Sema, byte: u8) !void {
+    const gpa = sema.gpa;
+    return sema.bytecode.append(gpa, byte);
+}
+
+fn emitByteOp(sema: *Sema, op: Story.Opcode) !void {
+    return emitByte(sema, @intFromEnum(op));
+}
+
+fn emitConstOp(sema: *Sema, op: Story.Opcode, arg: usize) !void {
+    const gpa = sema.gpa;
+    if (arg >= std.math.maxInt(u8)) return error.TooManyConstants;
+    try sema.bytecode.ensureUnusedCapacity(gpa, 2);
+    sema.bytecode.appendAssumeCapacity(@intFromEnum(op));
+    sema.bytecode.appendAssumeCapacity(@intCast(arg));
+}
+
+fn emitJumpOp(sema: *Sema, op: Story.Opcode) error{OutOfMemory}!usize {
+    const gpa = sema.gpa;
+    try sema.bytecode.ensureUnusedCapacity(gpa, 3);
+    sema.bytecode.appendAssumeCapacity(@intFromEnum(op));
+    sema.bytecode.appendAssumeCapacity(0xff);
+    sema.bytecode.appendAssumeCapacity(0xff);
+    return sema.bytecode.items.len - 2;
+}
+
+fn makeConstant(sema: *Sema, data: CompiledStory.Constant) !usize {
+    const gpa = sema.gpa;
+    const const_index = sema.constants.items.len;
+    try sema.constants.append(gpa, data);
+    return const_index;
+}
+
+fn unaryInst(sema: *Sema, _: Ir.Inst, op: Story.Opcode) InnerError!void {
+    return emitByteOp(sema, op);
+}
+
+fn binaryInst(sema: *Sema, _: Ir.Inst, op: Story.Opcode) InnerError!void {
+    return emitByteOp(sema, op);
+}
+
+fn contentInst(sema: *Sema, _: Ir.Inst) InnerError!void {
+    return emitByteOp(sema, .stream_flush);
+}
+
+fn blockInst(sema: *Sema, block_inst: Ir.Inst) InnerError!void {
+    const ir = sema.ir;
+    const extra = ir.extraData(Ir.Inst.Block, block_inst.data.payload.payload_index);
+    const body = ir.bodySlice(extra.end, extra.data.body_len);
+
+    for (body) |inst_index| {
+        const body_inst = resolveIndex(sema, inst_index);
+        try compileInst(sema, body_inst);
+    }
+}
+
+fn integerInst(sema: *Sema, inst: Ir.Inst) InnerError!void {
+    const int_const = try sema.makeConstant(.{
+        .integer = inst.data.integer.value,
+    });
+    return emitConstOp(sema, .load_const, int_const);
+}
+
+fn stringInst(sema: *Sema, inst: Ir.Inst) InnerError!void {
+    const str_const = try sema.makeConstant(.{
+        .string = inst.data.string.start,
+    });
+    return emitConstOp(sema, .load_const, str_const);
+}
+
+fn compileInst(sema: *Sema, inst: Ir.Inst) InnerError!void {
+    switch (inst.tag) {
+        .block => try blockInst(sema, inst),
+        .add => try binaryInst(sema, inst, .add),
+        .sub => try binaryInst(sema, inst, .sub),
+        .mul => try binaryInst(sema, inst, .mul),
+        .div => try binaryInst(sema, inst, .div),
+        .mod => try binaryInst(sema, inst, .mod),
+        .neg => try unaryInst(sema, inst, .neg),
+        .content => try contentInst(sema, inst),
+        .string => try stringInst(sema, inst),
+        .integer => try integerInst(sema, inst),
+        else => unreachable,
+    }
+}
+
+fn innerDecl(sema: *Sema, inst: Ir.Inst) !void {
+    const ir = sema.ir;
+    const extra = ir.extraData(Ir.Inst.Knot, inst.data.payload.payload_index);
+    const body_slice = ir.bodySlice(extra.end, extra.data.body_len);
+    for (body_slice) |inst_index| {
+        const body_inst = resolveIndex(sema, inst_index);
+        try compileInst(sema, body_inst);
+    }
+}
+
+fn declaration(sema: *Sema, inst: Ir.Inst) !void {
+    const gpa = sema.gpa;
+    const ir = sema.ir;
+    const byte_index = sema.bytecode.items.len;
+    const const_index = sema.constants.items.len;
+    const extra = ir.extraData(Ir.Inst.Declaration, inst.data.payload.payload_index);
+    const value_inst = sema.resolveIndex(extra.data.value);
+    switch (value_inst.tag) {
+        .decl_var => try innerDecl(sema, value_inst),
+        .decl_knot => try innerDecl(sema, value_inst),
+        else => unreachable,
+    }
+
+    const name_ref = extra.data.name;
+    try sema.knots.append(gpa, .{
+        .name_ref = name_ref,
+        .arity = 0,
+        .stack_size = 0,
+        .bytecode = .{
+            .start = @intCast(byte_index),
+            .len = @intCast(sema.bytecode.items.len - byte_index),
+        },
+        .constants = .{
+            .start = @intCast(const_index),
+            .len = @intCast(sema.constants.items.len - const_index),
+        },
+    });
+}
+
+fn file(sema: *Sema, inst: Ir.Inst) !void {
+    const extra = sema.ir.extraData(Ir.Inst.Block, inst.data.payload.payload_index);
+    const body = sema.ir.bodySlice(extra.end, extra.data.body_len);
+    for (body) |inst_index| {
+        const body_inst = sema.resolveIndex(inst_index);
+        switch (body_inst.tag) {
+            .declaration => try declaration(sema, body_inst),
+            else => unreachable,
+        }
+    }
+}
+
+pub const CompiledStory = struct {
+    knots: []Knot,
+    constants: []Constant,
+    bytecode: []u8,
+
+    pub const Knot = struct {
+        name_ref: Ir.NullTerminatedString,
+        arity: u32,
+        stack_size: u32,
+        constants: struct {
+            start: u32,
+            len: u32,
+        },
+        bytecode: struct {
+            start: u32,
+            len: u32,
+        },
+    };
+
+    pub const Constant = union(enum) {
+        integer: u64,
+        string: Ir.NullTerminatedString,
+    };
+
+    pub fn deinit(self: *CompiledStory, gpa: std.mem.Allocator) void {
+        gpa.free(self.knots);
+        gpa.free(self.bytecode);
+        gpa.free(self.constants);
+        self.* = undefined;
+    }
+
+    fn bytecodeSlice(self: CompiledStory, knot: *const Knot) []const u8 {
+        return self.bytecode[knot.bytecode.start..][0..knot.bytecode.len];
+    }
+
+    fn constantsSlice(self: CompiledStory, knot: *const Knot) []const Constant {
+        return self.constants[knot.constants.start..][0..knot.constants.len];
+    }
+
+    pub fn buildRuntime(
+        self: *CompiledStory,
+        gpa: std.mem.Allocator,
+        ir: Ir,
+        story: *Story,
+    ) !void {
+        for (self.knots) |compiled_knot| {
+            var constant_pool: std.ArrayListUnmanaged(*Object) = .empty;
+            try constant_pool.ensureUnusedCapacity(gpa, compiled_knot.constants.len);
+            defer constant_pool.deinit(gpa);
+
+            const constants_slice = self.constantsSlice(&compiled_knot);
+            for (constants_slice) |constant| {
+                switch (constant) {
+                    .integer => |value| {
+                        const object: *Object.Number = try .create(story, .{
+                            .integer = @intCast(value),
+                        });
+                        constant_pool.appendAssumeCapacity(&object.base);
+                    },
+                    .string => |ref| {
+                        const bytes = ir.nullTerminatedString(ref);
+                        const object: *Object.String = try .create(story, bytes);
+                        constant_pool.appendAssumeCapacity(&object.base);
+                    },
+                }
+            }
+
+            const bytecode_slice = self.bytecodeSlice(&compiled_knot);
+            const chunk_name = ir.nullTerminatedString(compiled_knot.name_ref);
+            const runtime_chunk: *Object.ContentPath = try .create(story, .{
+                .name = try .create(story, chunk_name),
+                .arity = @intCast(compiled_knot.arity),
+                .locals_count = @intCast(compiled_knot.stack_size - compiled_knot.arity),
+                .const_pool = try constant_pool.toOwnedSlice(gpa),
+                .bytes = try gpa.dupe(u8, bytecode_slice),
+            });
+            try story.paths.append(gpa, &runtime_chunk.base);
+        }
+    }
+};
+
+pub fn compile(gpa: std.mem.Allocator, ir: *const Ir) !CompiledStory {
+    var sema: Sema = .{
+        .gpa = gpa,
+        .ir = ir,
+    };
+    defer sema.deinit();
+
+    try file(&sema, ir.instructions[0]);
+    return .{
+        .bytecode = try sema.bytecode.toOwnedSlice(gpa),
+        .constants = try sema.constants.toOwnedSlice(gpa),
+        .knots = try sema.knots.toOwnedSlice(gpa),
+    };
+}
diff --git a/src/Story.zig b/src/Story.zig
index 4ed0fe7..47bb43d 100644
--- a/src/Story.zig
+++ b/src/Story.zig
@@ -3,6 +3,7 @@ const std = @import("std");
 const tokenizer = @import("tokenizer.zig");
 const Ast = @import("Ast.zig");
 const AstGen = @import("AstGen.zig");
+const Sema = @import("Sema.zig");
 pub const Object = @import("Story/object.zig").Object;
 const Dumper = @import("Story/Dumper.zig");
 const assert = std.debug.assert;
@@ -481,11 +482,11 @@ pub fn loadFromString(
 ) !Story {
     var arena_allocator = std.heap.ArenaAllocator.init(gpa);
     defer arena_allocator.deinit();
-
     const arena = arena_allocator.allocator();
     const ast = try Ast.parse(gpa, arena, source_bytes, "<STDIN>", 0);
 
     if (options.dump_writer) |w| {
+        try w.writeAll("=== AST ===\n");
         try ast.render(gpa, w, .{
             .use_color = options.use_color,
         });
@@ -497,48 +498,25 @@ pub fn loadFromString(
         return error.Invalid;
     }
 
-    const comp_unit = try AstGen.generate(gpa, &ast);
-    defer comp_unit.deinit(gpa);
-    comp_unit.dumpStringsWithHex();
+    var sem_ir = try AstGen.generate(gpa, &ast);
+    defer sem_ir.deinit(gpa);
+
+    if (options.dump_writer) |w| {
+        try w.writeAll("=== Semantic IR ===\n");
+        sem_ir.dumpStringsWithHex();
+        try sem_ir.render(gpa, w);
+    }
+
+    var compiled = try Sema.compile(gpa, &sem_ir);
+    defer compiled.deinit(gpa);
 
     var story: Story = .{
         .allocator = gpa,
         .can_advance = false,
         .dump_writer = options.dump_writer,
     };
-    errdefer story.deinit();
-
-    for (comp_unit.knots) |compiled_chunk| {
-        const chunk_name = comp_unit.resolveString(compiled_chunk.name_ref);
-        var constant_pool: std.ArrayList(*Object) = .empty;
-        try constant_pool.ensureUnusedCapacity(gpa, compiled_chunk.constants.len);
-        defer constant_pool.deinit(gpa);
-
-        for (comp_unit.resolveConstants(compiled_chunk.constants)) |constant| {
-            switch (constant) {
-                .number => |value| {
-                    const object: *Object.Number = try .create(&story, .{ .integer = value });
-                    constant_pool.appendAssumeCapacity(&object.base);
-                },
-                .string => |ref| {
-                    const bytes = comp_unit.resolveString(ref);
-                    const object: *Object.String = try .create(&story, bytes);
-                    constant_pool.appendAssumeCapacity(&object.base);
-                },
-            }
-        }
-
-        const runtime_chunk: *Object.ContentPath = try .create(&story, .{
-            .name = try .create(&story, chunk_name),
-            .arity = @intCast(compiled_chunk.arity),
-            .locals_count = @intCast(compiled_chunk.stack_size - compiled_chunk.arity),
-            .const_pool = try constant_pool.toOwnedSlice(gpa),
-            .bytes = try gpa.dupe(u8, comp_unit.resolveInstructions(compiled_chunk.instructions)),
-        });
-        try story.paths.append(gpa, &runtime_chunk.base);
-    }
-
-    try story.divert("$__main__$");
-    story.can_advance = true;
+    try compiled.buildRuntime(gpa, sem_ir, &story);
+    // try story.divert("$__main__$");
+    // story.can_advance = true;
     return story;
 }