diff --git a/src/generators/Generator.ts b/src/generators/Generator.ts
index 48491e410c..330f824333 100644
--- a/src/generators/Generator.ts
+++ b/src/generators/Generator.ts
@@ -16,6 +16,7 @@ import DomBlock from './dom/Block';
 import SsrBlock from './server-side-rendering/Block';
 import Stylesheet from '../css/Stylesheet';
 import { Node, GenerateOptions, Parsed, CompileOptions } from '../interfaces';
+import { Computation, TemplateProperties } from './interfaces';
 
 const test = typeof global !== 'undefined' && global.__svelte_test;
 
@@ -26,12 +27,18 @@ export default class Generator {
 	name: string;
 	options: CompileOptions;
 
+	defaultExport: Node[];
 	imports: Node[];
 	helpers: Set<string>;
 	components: Set<string>;
 	events: Set<string>;
 	transitions: Set<string>;
 	importedComponents: Map<string, string>;
+	namespace: string;
+	hasComponents: boolean;
+	hasJs: boolean;
+	computations: Computation[];
+	templateProperties: TemplateProperties;
 
 	code: MagicString;
 
@@ -379,9 +386,9 @@ export default class Generator {
 		return alias;
 	}
 
-	getUniqueNameMaker(params) {
+	getUniqueNameMaker(params: string[]) {
 		const localUsedNames = new Set(params);
-		return name => {
+		return (name: string) => {
 			if (test) name = `${name}$`;
 			let alias = name;
 			for (
@@ -402,8 +409,8 @@ export default class Generator {
 		const { js } = this.parsed;
 
 		const imports = this.imports;
-		const computations = [];
-		const templateProperties = {};
+		const computations: Computation[] = [];
+		const templateProperties: TemplateProperties = {};
 
 		let namespace = null;
 		let hasJs = !!js;
@@ -459,7 +466,7 @@ export default class Generator {
 
 				const visited = new Set();
 
-				function visit(key) {
+				function visit(key: string) {
 					if (!dependencies.has(key)) return; // not a computation
 
 					if (visited.has(key)) return;
diff --git a/src/generators/dom/index.ts b/src/generators/dom/index.ts
index 073471e5b0..03cdd0d7bd 100644
--- a/src/generators/dom/index.ts
+++ b/src/generators/dom/index.ts
@@ -317,7 +317,7 @@ export default function dom(
 			let scope = annotateWithScopes(expression);
 
 			walk(expression, {
-				enter(node, parent) {
+				enter(node: Node, parent: Node) {
 					if (node._scope) scope = node._scope;
 
 					if (
@@ -337,7 +337,7 @@ export default function dom(
 					}
 				},
 
-				leave(node) {
+				leave(node: Node) {
 					if (node._scope) scope = scope.parent;
 				},
 			});
diff --git a/src/generators/dom/interfaces.ts b/src/generators/dom/interfaces.ts
index 03923b79bf..858680b7df 100644
--- a/src/generators/dom/interfaces.ts
+++ b/src/generators/dom/interfaces.ts
@@ -1,5 +1,5 @@
 export interface State {
-	name: string;
+	name?: string;
 	namespace: string;
 	parentNode: string;
 	parentNodes: string;
diff --git a/src/generators/interfaces.ts b/src/generators/interfaces.ts
new file mode 100644
index 0000000000..795122a8b5
--- /dev/null
+++ b/src/generators/interfaces.ts
@@ -0,0 +1,23 @@
+import { Node } from '../interfaces';
+
+export interface Computation {
+	key: string;
+	deps: string[]
+}
+
+export interface TemplateProperties {
+	computed?: Node;
+	components?: Node;
+	data?: Node;
+	events?: Node;
+	helpers?: Node;
+	methods?: Node;
+	namespace?: Node;
+	oncreate?: Node;
+	ondestroy?: Node;
+	transitions?: Node;
+
+	// TODO remove in v2
+	onrender?: Node;
+	onteardown?: Node;
+}
\ No newline at end of file
diff --git a/src/interfaces.ts b/src/interfaces.ts
index 4944bf8c46..fc0a6b1147 100644
--- a/src/interfaces.ts
+++ b/src/interfaces.ts
@@ -34,8 +34,10 @@ export interface Warning {
 	toString: () => string;
 }
 
+export type ModuleFormat = 'es' | 'amd' | 'cjs' | 'iife' | 'umd' | 'eval';
+
 export interface CompileOptions {
-	format?: string;
+	format?: ModuleFormat;
 	name?: string;
 	filename?: string;
 	generate?: string;
@@ -56,8 +58,6 @@ export interface CompileOptions {
 	onwarn?: (warning: Warning) => void;
 }
 
-export type ModuleFormat = 'es' | 'amd' | 'cjs' | 'iife' | 'umd' | 'eval';
-
 export interface GenerateOptions {
 	name: string;
 	format: ModuleFormat;
diff --git a/src/parse/read/directives.ts b/src/parse/read/directives.ts
index 0b61ad6350..c0c46d6af9 100644
--- a/src/parse/read/directives.ts
+++ b/src/parse/read/directives.ts
@@ -2,7 +2,7 @@ import { parseExpressionAt } from 'acorn';
 import spaces from '../../utils/spaces';
 import { Parser } from '../index';
 
-function readExpression(parser: Parser, start: number, quoteMark) {
+function readExpression(parser: Parser, start: number, quoteMark: string|null) {
 	let str = '';
 	let escaped = false;
 
diff --git a/src/parse/read/script.ts b/src/parse/read/script.ts
index 4d4a8559a1..42e8729e06 100644
--- a/src/parse/read/script.ts
+++ b/src/parse/read/script.ts
@@ -1,10 +1,11 @@
 import { parse } from 'acorn';
 import spaces from '../../utils/spaces';
 import { Parser } from '../index';
+import { Node } from '../../interfaces';
 
 const scriptClosingTag = '</script>';
 
-export default function readScript(parser: Parser, start: number, attributes) {
+export default function readScript(parser: Parser, start: number, attributes: Node[]) {
 	const scriptStart = parser.index;
 	const scriptEnd = parser.template.indexOf(scriptClosingTag, scriptStart);
 
diff --git a/src/parse/read/style.ts b/src/parse/read/style.ts
index d1882d67df..d12cd0ab41 100644
--- a/src/parse/read/style.ts
+++ b/src/parse/read/style.ts
@@ -1,8 +1,9 @@
 import parse from 'css-tree/lib/parser/index.js';
 import walk from 'css-tree/lib/utils/walk.js';
 import { Parser } from '../index';
+import { Node } from '../../interfaces';
 
-export default function readStyle(parser: Parser, start: number, attributes) {
+export default function readStyle(parser: Parser, start: number, attributes: Node[]) {
 	const contentStart = parser.index;
 	const styles = parser.readUntil(/<\/style>/);
 	const contentEnd = parser.index;
@@ -23,7 +24,7 @@ export default function readStyle(parser: Parser, start: number, attributes) {
 	}
 
 	// tidy up AST
-	walk.all(ast, node => {
+	walk.all(ast, (node: Node) => {
 		if (node.loc) {
 			node.start = node.loc.start.offset;
 			node.end = node.loc.end.offset;
diff --git a/src/parse/state/mustache.ts b/src/parse/state/mustache.ts
index 716f20d288..88107af750 100644
--- a/src/parse/state/mustache.ts
+++ b/src/parse/state/mustache.ts
@@ -6,7 +6,7 @@ import { Node } from '../../interfaces';
 
 const validIdentifier = /[a-zA-Z_$][a-zA-Z0-9_$]*/;
 
-function trimWhitespace(block, trimBefore, trimAfter) {
+function trimWhitespace(block: Node, trimBefore: boolean, trimAfter: boolean) {
 	const firstChild = block.children[0];
 	const lastChild = block.children[block.children.length - 1];
 
@@ -220,6 +220,4 @@ export default function mustache(parser: Parser) {
 			expression,
 		});
 	}
-
-	return null;
 }
diff --git a/src/parse/state/tag.ts b/src/parse/state/tag.ts
index cfa0561365..c77127b53f 100644
--- a/src/parse/state/tag.ts
+++ b/src/parse/state/tag.ts
@@ -78,7 +78,7 @@ export default function tag(parser: Parser) {
 			data,
 		});
 
-		return null;
+		return;
 	}
 
 	const isClosingTag = parser.eat('/');
@@ -133,7 +133,7 @@ export default function tag(parser: Parser) {
 		parent.end = parser.index;
 		parser.stack.pop();
 
-		return null;
+		return;
 	} else if (disallowedContents.has(parent.name)) {
 		// can this be a child of the parent element, or does it implicitly
 		// close it, like `<li>one<li>two`?
@@ -200,8 +200,6 @@ export default function tag(parser: Parser) {
 		// don't push self-closing elements onto the stack
 		parser.stack.push(element);
 	}
-
-	return null;
 }
 
 function readTagName(parser: Parser) {
@@ -242,7 +240,7 @@ function readTagName(parser: Parser) {
 	return name;
 }
 
-function readAttribute(parser: Parser, uniqueNames) {
+function readAttribute(parser: Parser, uniqueNames: Set<string>) {
 	const start = parser.index;
 
 	let name = parser.readUntil(/(\s|=|\/|>)/);
diff --git a/src/parse/state/text.ts b/src/parse/state/text.ts
index 0f85040c21..bdd625569c 100644
--- a/src/parse/state/text.ts
+++ b/src/parse/state/text.ts
@@ -20,6 +20,4 @@ export default function text(parser: Parser) {
 		type: 'Text',
 		data: decodeCharacterReferences(data),
 	});
-
-	return null;
 }