diff --git a/src/generators/Generator.ts b/src/generators/Generator.ts
index ccc31d8aec..fc87740e5a 100644
--- a/src/generators/Generator.ts
+++ b/src/generators/Generator.ts
@@ -176,7 +176,7 @@ export default class Generator {
 		};
 	}
 
-	findDependencies ( contextDependencies, indexes, expression ) {
+	findDependencies ( contextDependencies: Map<string, string[]>, indexes: Map<string, string>, expression: Node ) {
 		if ( expression._dependencies ) return expression._dependencies;
 
 		let scope = annotateWithScopes( expression );
@@ -340,23 +340,23 @@ export default class Generator {
 					removeNode( this.code, js.content, node );
 					imports.push( node );
 
-					node.specifiers.forEach( specifier => {
+					node.specifiers.forEach( ( specifier: Node ) => {
 						this.importedNames.add( specifier.local.name );
 					});
 				}
 			}
 
-			const defaultExport = body.find( node => node.type === 'ExportDefaultDeclaration' );
+			const defaultExport = body.find( ( node: Node ) => node.type === 'ExportDefaultDeclaration' );
 
 			if ( defaultExport ) {
-				defaultExport.declaration.properties.forEach( prop => {
+				defaultExport.declaration.properties.forEach( ( prop: Node ) => {
 					templateProperties[ prop.key.name ] = prop;
 				});
 			}
 
 			[ 'helpers', 'events', 'components', 'transitions' ].forEach( key => {
 				if ( templateProperties[ key ] ) {
-					templateProperties[ key ].value.properties.forEach( prop => {
+					templateProperties[ key ].value.properties.forEach( ( prop: node ) => {
 						this[ key ].add( prop.key.name );
 					});
 				}
@@ -365,11 +365,11 @@ export default class Generator {
 			if ( templateProperties.computed ) {
 				const dependencies = new Map();
 
-				templateProperties.computed.value.properties.forEach( prop => {
+				templateProperties.computed.value.properties.forEach( ( prop: Node ) => {
 					const key = prop.key.name;
 					const value = prop.value;
 
-					const deps = value.params.map( param => param.type === 'AssignmentPattern' ? param.left.name : param.name );
+					const deps = value.params.map( ( param: Node ) => param.type === 'AssignmentPattern' ? param.left.name : param.name );
 					dependencies.set( key, deps );
 				});
 
@@ -387,7 +387,7 @@ export default class Generator {
 					computations.push({ key, deps });
 				}
 
-				templateProperties.computed.value.properties.forEach( prop => visit( prop.key.name ) );
+				templateProperties.computed.value.properties.forEach( ( prop: Node ) => visit( prop.key.name ) );
 			}
 
 			if ( templateProperties.namespace ) {
@@ -399,7 +399,7 @@ export default class Generator {
 
 			if ( templateProperties.components ) {
 				let hasNonImportedComponent = false;
-				templateProperties.components.value.properties.forEach( property => {
+				templateProperties.components.value.properties.forEach( ( property: Node ) => {
 					const key = property.key.name;
 					const value = source.slice( property.value.start, property.value.end );
 					if ( this.importedNames.has( value ) ) {
diff --git a/src/generators/dom/Block.ts b/src/generators/dom/Block.ts
index 9683cf6556..9523d42e7c 100644
--- a/src/generators/dom/Block.ts
+++ b/src/generators/dom/Block.ts
@@ -4,11 +4,20 @@ import { DomGenerator } from './index';
 import { Node } from '../../interfaces';
 
 export interface BlockOptions {
-	generator: DomGenerator;
 	name: string;
-	expression: Node;
-	context: string;
-	key: string;
+	generator?: DomGenerator;
+	expression?: Node;
+	context?: string;
+	key?: string;
+	contexts?: Map<string, string>;
+	indexes?: Map<string, string>;
+	contextDependencies?: Map<string, string[]>;
+	params?: string[];
+	indexNames?: Map<string, string>;
+	listNames?: Map<string, string>;
+	indexName?: string;
+	listName?: string;
+	dependencies?: Set<string>;
 }
 
 export default class Block {
@@ -16,7 +25,19 @@ export default class Block {
 	name: string;
 	expression: Node;
 	context: string;
+
 	key: string;
+	first: string;
+
+	contexts: Map<string, string>;
+	indexes: Map<string, string>;
+	contextDependencies: Map<string, string[]>;
+	dependencies: Set<string>;
+	params: string[];
+	indexNames: Map<string, string>;
+	listNames: Map<string, string>;
+	indexName: string;
+	listName: string;
 
 	builders: {
 		create: CodeBuilder;
@@ -41,6 +62,7 @@ export default class Block {
 	target: string;
 
 	hasUpdateMethod: boolean;
+	autofocus: string;
 
 	constructor ( options: BlockOptions ) {
 		this.generator = options.generator;
@@ -95,7 +117,7 @@ export default class Block {
 		});
 	}
 
-	addElement ( name: string, renderStatement: string, parentNode, needsIdentifier = false ) {
+	addElement ( name: string, renderStatement: string, parentNode: string, needsIdentifier = false ) {
 		const isToplevel = !parentNode;
 		if ( needsIdentifier || isToplevel ) {
 			this.builders.create.addLine(
diff --git a/src/generators/dom/index.ts b/src/generators/dom/index.ts
index d2d02ff14d..dc112bb4ca 100644
--- a/src/generators/dom/index.ts
+++ b/src/generators/dom/index.ts
@@ -18,6 +18,10 @@ export class DomGenerator extends Generator {
 	readonly: Set<string>;
 	metaBindings: string[];
 
+	hasIntroTransitions: boolean;
+	hasOutroTransitions: boolean;
+	hasComplexBindings: boolean;
+
 	constructor ( parsed: Parsed, source: string, name: string, options: CompileOptions ) {
 		super( parsed, source, name, options );
 		this.blocks = [];
@@ -48,13 +52,7 @@ export default function dom ( parsed: Parsed, source: string, options: CompileOp
 
 	const { computations, hasJs, templateProperties, namespace } = generator.parseJs();
 
-	const state = {
-		namespace,
-		parentNode: null,
-		isTopLevel: true
-	};
-
-	const block = preprocess( generator, state, parsed.html );
+	const { block, state } = preprocess( generator, namespace, parsed.html );
 
 	parsed.html.children.forEach( ( node: Node ) => {
 		visit( generator, block, state, node );
diff --git a/src/generators/dom/interfaces.ts b/src/generators/dom/interfaces.ts
new file mode 100644
index 0000000000..6385d93566
--- /dev/null
+++ b/src/generators/dom/interfaces.ts
@@ -0,0 +1,10 @@
+export interface State {
+	namespace: string;
+	parentNode: string;
+	isTopLevel: boolean
+	parentNodeName?: string;
+	basename?: string;
+	inEachBlock?: boolean;
+	allUsedContexts?: string[];
+	usesComponent?: boolean;
+}
\ No newline at end of file
diff --git a/src/generators/dom/preprocess.ts b/src/generators/dom/preprocess.ts
index 1ea44a6855..3a96aca3f2 100644
--- a/src/generators/dom/preprocess.ts
+++ b/src/generators/dom/preprocess.ts
@@ -3,12 +3,13 @@ import { trimStart, trimEnd } from '../../utils/trim';
 import { assign } from '../../shared/index.js';
 import { DomGenerator } from './index';
 import { Node } from '../../interfaces';
+import { State } from './interfaces';
 
 function isElseIf ( node: Node ) {
 	return node && node.children.length === 1 && node.children[0].type === 'IfBlock';
 }
 
-function getChildState ( parent, child = {} ) {
+function getChildState ( parent: State, child = {} ) {
 	return assign( {}, parent, { name: null, parentNode: null }, child || {} );
 }
 
@@ -27,7 +28,7 @@ const elementsWithoutText = new Set([
 ]);
 
 const preprocessors = {
-	MustacheTag: ( generator: DomGenerator, block, state, node: Node ) => {
+	MustacheTag: ( generator: DomGenerator, block: Block, state: State, node: Node ) => {
 		const dependencies = block.findDependencies( node.expression );
 		block.addDependencies( dependencies );
 
@@ -36,7 +37,7 @@ const preprocessors = {
 		});
 	},
 
-	RawMustacheTag: ( generator: DomGenerator, block, state, node: Node ) => {
+	RawMustacheTag: ( generator: DomGenerator, block: Block, state: State, node: Node ) => {
 		const dependencies = block.findDependencies( node.expression );
 		block.addDependencies( dependencies );
 
@@ -46,7 +47,7 @@ const preprocessors = {
 		node._state = getChildState( state, { basename, name });
 	},
 
-	Text: ( generator: DomGenerator, block, state, node: Node ) => {
+	Text: ( generator: DomGenerator, block: Block, state: State, node: Node ) => {
 		node._state = getChildState( state );
 
 		if ( !/\S/.test( node.data ) ) {
@@ -58,8 +59,8 @@ const preprocessors = {
 		node._state.name = block.getUniqueName( `text` );
 	},
 
-	IfBlock: ( generator: DomGenerator, block, state, node: Node ) => {
-		const blocks = [];
+	IfBlock: ( generator: DomGenerator, block: Block, state: State, node: Node ) => {
+		const blocks: Block[] = [];
 		let dynamic = false;
 		let hasIntros = false;
 		let hasOutros = false;
@@ -115,7 +116,7 @@ const preprocessors = {
 		generator.blocks.push( ...blocks );
 	},
 
-	EachBlock: ( generator: DomGenerator, block, state, node: Node ) => {
+	EachBlock: ( generator: DomGenerator, block: Block, state: State, node: Node ) => {
 		const dependencies = block.findDependencies( node.expression );
 		block.addDependencies( dependencies );
 
@@ -177,7 +178,7 @@ const preprocessors = {
 		}
 	},
 
-	Element: ( generator: DomGenerator, block, state, node: Node ) => {
+	Element: ( generator: DomGenerator, block: Block, state: State, node: Node ) => {
 		const isComponent = generator.components.has( node.name ) || node.name === ':Self';
 
 		if ( isComponent ) {
@@ -240,7 +241,7 @@ const preprocessors = {
 	}
 };
 
-function preprocessChildren ( generator: DomGenerator, block, state, node: Node, isTopLevel: boolean ) {
+function preprocessChildren ( generator: DomGenerator, block: Block, state: State, node: Node, isTopLevel: boolean = false ) {
 	// glue text nodes together
 	const cleaned: Node[] = [];
 	let lastChild: Node;
@@ -294,7 +295,7 @@ function preprocessChildren ( generator: DomGenerator, block, state, node: Node,
 	node.children = cleaned;
 }
 
-export default function preprocess ( generator: DomGenerator, state, node ) {
+export default function preprocess ( generator: DomGenerator, namespace: string, node: Node ) {
 	const block = new Block({
 		generator,
 		name: generator.alias( 'create_main_fragment' ),
@@ -311,9 +312,15 @@ export default function preprocess ( generator: DomGenerator, state, node ) {
 		dependencies: new Set()
 	});
 
+	const state: State = {
+		namespace,
+		parentNode: null,
+		isTopLevel: true
+	};
+
 	generator.blocks.push( block );
 	preprocessChildren( generator, block, state, node, true );
 	block.hasUpdateMethod = block.dependencies.size > 0;
 
-	return block;
+	return { block, state };
 }
\ No newline at end of file
diff --git a/src/generators/dom/visitors/Component/Attribute.ts b/src/generators/dom/visitors/Component/Attribute.ts
index 0055c75e0a..690cb88639 100644
--- a/src/generators/dom/visitors/Component/Attribute.ts
+++ b/src/generators/dom/visitors/Component/Attribute.ts
@@ -1,8 +1,9 @@
 import { DomGenerator } from '../../index';
 import Block from '../../Block';
 import { Node } from '../../../../interfaces';
+import { State } from '../../interfaces';
 
-export default function visitAttribute ( generator: DomGenerator, block: Block, state, node: Node, attribute, local ) {
+export default function visitAttribute ( generator: DomGenerator, block: Block, state: State, node: Node, attribute, local ) {
 	if ( attribute.value === true ) {
 		// attributes without values, e.g. <textarea readonly>
 		local.staticAttributes.push({
diff --git a/src/generators/dom/visitors/Component/Binding.ts b/src/generators/dom/visitors/Component/Binding.ts
index e13db9b5b6..724901dea1 100644
--- a/src/generators/dom/visitors/Component/Binding.ts
+++ b/src/generators/dom/visitors/Component/Binding.ts
@@ -4,8 +4,9 @@ import getSetter from '../shared/binding/getSetter';
 import { DomGenerator } from '../../index';
 import Block from '../../Block';
 import { Node } from '../../../../interfaces';
+import { State } from '../../interfaces';
 
-export default function visitBinding ( generator: DomGenerator, block: Block, state, node: Node, attribute, local ) {
+export default function visitBinding ( generator: DomGenerator, block: Block, state: State, node: Node, attribute, local ) {
 	const { name } = flattenReference( attribute.value );
 	const { snippet, contexts, dependencies } = block.contextualise( attribute.value );
 
diff --git a/src/generators/dom/visitors/Component/Component.ts b/src/generators/dom/visitors/Component/Component.ts
index ffbef826b4..3877e64a7d 100644
--- a/src/generators/dom/visitors/Component/Component.ts
+++ b/src/generators/dom/visitors/Component/Component.ts
@@ -8,8 +8,9 @@ import visitRef from './Ref';
 import { DomGenerator } from '../../index';
 import Block from '../../Block';
 import { Node } from '../../../../interfaces';
+import { State } from '../../interfaces';
 
-function stringifyProps ( props ) {
+function stringifyProps ( props: string[] ) {
 	if ( !props.length ) return '{}';
 
 	const joined = props.join( ', ' );
@@ -35,7 +36,7 @@ const visitors = {
 	Ref: visitRef
 };
 
-export default function visitComponent ( generator: DomGenerator, block: Block, state, node: Node ) {
+export default function visitComponent ( generator: DomGenerator, block: Block, state: State, node: Node ) {
 	const hasChildren = node.children.length > 0;
 	const name = block.getUniqueName( ( node.name === ':Self' ? generator.name : node.name ).toLowerCase() );
 
@@ -123,7 +124,7 @@ export default function visitComponent ( generator: DomGenerator, block: Block,
 		componentInitProperties.push( `_yield: ${yieldFragment}`);
 	}
 
-	const statements = [];
+	const statements: string[] = [];
 
 	if ( local.staticAttributes.length || local.dynamicAttributes.length || local.bindings.length ) {
 		const initialProps = local.staticAttributes
diff --git a/src/generators/dom/visitors/Component/EventHandler.ts b/src/generators/dom/visitors/Component/EventHandler.ts
index bfbed60f99..41f2b42b5a 100644
--- a/src/generators/dom/visitors/Component/EventHandler.ts
+++ b/src/generators/dom/visitors/Component/EventHandler.ts
@@ -2,14 +2,15 @@ import deindent from '../../../../utils/deindent.js';
 import { DomGenerator } from '../../index';
 import Block from '../../Block';
 import { Node } from '../../../../interfaces';
+import { State } from '../../interfaces';
 
-export default function visitEventHandler ( generator: DomGenerator, block: Block, state, node: Node, attribute, local ) {
+export default function visitEventHandler ( generator: DomGenerator, block: Block, state: State, node: Node, attribute: Node, local ) {
 	// TODO verify that it's a valid callee (i.e. built-in or declared method)
 	generator.addSourcemapLocations( attribute.expression );
 	generator.code.prependRight( attribute.expression.start, `${block.component}.` );
 
-	const usedContexts = [];
-	attribute.expression.arguments.forEach( arg => {
+	const usedContexts: string[] = [];
+	attribute.expression.arguments.forEach( ( arg: Node ) => {
 		const { contexts } = block.contextualise( arg, null, true );
 
 		contexts.forEach( context => {
diff --git a/src/generators/dom/visitors/Component/Ref.ts b/src/generators/dom/visitors/Component/Ref.ts
index 2dbff21133..480af0d11c 100644
--- a/src/generators/dom/visitors/Component/Ref.ts
+++ b/src/generators/dom/visitors/Component/Ref.ts
@@ -2,8 +2,9 @@ import deindent from '../../../../utils/deindent.js';
 import { DomGenerator } from '../../index';
 import Block from '../../Block';
 import { Node } from '../../../../interfaces';
+import { State } from '../../interfaces';
 
-export default function visitRef ( generator: DomGenerator, block: Block, state, node: Node, attribute, local ) {
+export default function visitRef ( generator: DomGenerator, block: Block, state: State, node: Node, attribute: Node, local ) {
 	generator.usesRefs = true;
 
 	local.create.addLine(
diff --git a/src/generators/dom/visitors/EachBlock.ts b/src/generators/dom/visitors/EachBlock.ts
index f4260a813f..8ead975c82 100644
--- a/src/generators/dom/visitors/EachBlock.ts
+++ b/src/generators/dom/visitors/EachBlock.ts
@@ -3,8 +3,9 @@ import visit from '../visit';
 import { DomGenerator } from '../index';
 import Block from '../Block';
 import { Node } from '../../../interfaces';
+import { State } from '../interfaces';
 
-export default function visitEachBlock ( generator: DomGenerator, block: Block, state, node: Node ) {
+export default function visitEachBlock ( generator: DomGenerator, block: Block, state: State, node: Node ) {
 	const each_block = generator.getUniqueName( `each_block` );
 	const create_each_block = node._block.name;
 	const each_block_value = node._block.listName;
@@ -100,7 +101,7 @@ export default function visitEachBlock ( generator: DomGenerator, block: Block,
 	}
 }
 
-function keyed ( generator: DomGenerator, block: Block, state, node: Node, snippet, { each_block, create_each_block, each_block_value, i, params, anchor, mountOrIntro } ) {
+function keyed ( generator: DomGenerator, block: Block, state: State, node: Node, snippet, { each_block, create_each_block, each_block_value, i, params, anchor, mountOrIntro } ) {
 	const key = block.getUniqueName( 'key' );
 	const lookup = block.getUniqueName( `${each_block}_lookup` );
 	const iteration = block.getUniqueName( `${each_block}_iteration` );
@@ -274,7 +275,7 @@ function keyed ( generator: DomGenerator, block: Block, state, node: Node, snipp
 	` );
 }
 
-function unkeyed ( generator: DomGenerator, block: Block, state, node: Node, snippet, { create_each_block, each_block_value, iterations, i, params, anchor, mountOrIntro } ) {
+function unkeyed ( generator: DomGenerator, block: Block, state: State, node: Node, snippet, { create_each_block, each_block_value, iterations, i, params, anchor, mountOrIntro } ) {
 	block.builders.create.addBlock( deindent`
 		var ${iterations} = [];
 
diff --git a/src/generators/dom/visitors/Element/Attribute.ts b/src/generators/dom/visitors/Element/Attribute.ts
index 18b9666d54..7252eb6886 100644
--- a/src/generators/dom/visitors/Element/Attribute.ts
+++ b/src/generators/dom/visitors/Element/Attribute.ts
@@ -4,8 +4,9 @@ import getStaticAttributeValue from './getStaticAttributeValue';
 import { DomGenerator } from '../../index';
 import Block from '../../Block';
 import { Node } from '../../../../interfaces';
+import { State } from '../../interfaces';
 
-export default function visitAttribute ( generator: DomGenerator, block: Block, state, node: Node, attribute ) {
+export default function visitAttribute ( generator: DomGenerator, block: Block, state: State, node: Node, attribute: Node ) {
 	const name = attribute.name;
 
 	let metadata = state.namespace ? null : attributeLookup[ name ];
@@ -35,7 +36,7 @@ export default function visitAttribute ( generator: DomGenerator, block: Block,
 		} else {
 			// '{{foo}} {{bar}}' — treat as string concatenation
 			value = ( attribute.value[0].type === 'Text' ? '' : `"" + ` ) + (
-				attribute.value.map( chunk => {
+				attribute.value.map( ( chunk: Node ) => {
 					if ( chunk.type === 'Text' ) {
 						return JSON.stringify( chunk.data );
 					} else {
diff --git a/src/generators/dom/visitors/Element/Binding.ts b/src/generators/dom/visitors/Element/Binding.ts
index 049c6c5a3c..4b0cfc3d09 100644
--- a/src/generators/dom/visitors/Element/Binding.ts
+++ b/src/generators/dom/visitors/Element/Binding.ts
@@ -5,8 +5,9 @@ import getStaticAttributeValue from './getStaticAttributeValue';
 import { DomGenerator } from '../../index';
 import Block from '../../Block';
 import { Node } from '../../../../interfaces';
+import { State } from '../../interfaces';
 
-export default function visitBinding ( generator: DomGenerator, block: Block, state, node: Node, attribute ) {
+export default function visitBinding ( generator: DomGenerator, block: Block, state: State, node: Node, attribute: Node ) {
 	const { name, parts } = flattenReference( attribute.value );
 	const { snippet, contexts, dependencies } = block.contextualise( attribute.value );
 
@@ -18,7 +19,7 @@ export default function visitBinding ( generator: DomGenerator, block: Block, st
 
 	const eventName = getBindingEventName( node, attribute );
 	const handler = block.getUniqueName( `${state.parentNode}_${eventName}_handler` );
-	const isMultipleSelect = node.name === 'select' && node.attributes.find( attr => attr.name.toLowerCase() === 'multiple' ); // TODO use getStaticAttributeValue
+	const isMultipleSelect = node.name === 'select' && node.attributes.find( ( attr: Node ) => attr.name.toLowerCase() === 'multiple' ); // TODO use getStaticAttributeValue
 	const type = getStaticAttributeValue( node, 'type' );
 	const bindingGroup = attribute.name === 'group' ? getBindingGroup( generator, parts.join( '.' ) ) : null;
 	const value = getBindingValue( generator, block, state, node, attribute, isMultipleSelect, bindingGroup, type );
@@ -144,9 +145,9 @@ export default function visitBinding ( generator: DomGenerator, block: Block, st
 	}
 }
 
-function getBindingEventName ( node, attribute ) {
+function getBindingEventName ( node: Node, attribute: Node ) {
 	if ( node.name === 'input' ) {
-		const typeAttribute = node.attributes.find( attr => attr.type === 'Attribute' && attr.name === 'type' );
+		const typeAttribute = node.attributes.find( ( attr: Node ) => attr.type === 'Attribute' && attr.name === 'type' );
 		const type = typeAttribute ? typeAttribute.value[0].data : 'text'; // TODO in validation, should throw if type attribute is not static
 
 		return type === 'checkbox' || type === 'radio' ? 'change' : 'input';
@@ -160,7 +161,7 @@ function getBindingEventName ( node, attribute ) {
 	return 'change';
 }
 
-function getBindingValue ( generator, block, state, node, attribute, isMultipleSelect, bindingGroup, type ) {
+function getBindingValue ( generator: DomGenerator, block: Block, state: State, node: Node, attribute: Node, isMultipleSelect: boolean, bindingGroup: number, type: string ) {
 	// <select multiple bind:value='selected>
 	if ( isMultipleSelect ) {
 		return `[].map.call( ${state.parentNode}.querySelectorAll(':checked'), function ( option ) { return option.__value; })`;
@@ -189,7 +190,7 @@ function getBindingValue ( generator, block, state, node, attribute, isMultipleS
 	return `${state.parentNode}.${attribute.name}`;
 }
 
-function getBindingGroup ( generator, keypath ) {
+function getBindingGroup ( generator: DomGenerator, keypath: string ) {
 	// TODO handle contextual bindings — `keypath` should include unique ID of
 	// each block that provides context
 	let index = generator.bindingGroups.indexOf( keypath );
diff --git a/src/generators/dom/visitors/Element/Element.ts b/src/generators/dom/visitors/Element/Element.ts
index f0063a3c12..a5974f9485 100644
--- a/src/generators/dom/visitors/Element/Element.ts
+++ b/src/generators/dom/visitors/Element/Element.ts
@@ -10,6 +10,7 @@ import addTransitions from './addTransitions';
 import { DomGenerator } from '../../index';
 import Block from '../../Block';
 import { Node } from '../../../../interfaces';
+import { State } from '../../interfaces';
 
 const meta = {
 	':Window': visitWindow
@@ -29,7 +30,7 @@ const visitors = {
 	Ref: visitRef
 };
 
-export default function visitElement ( generator: DomGenerator, block: Block, state, node: Node ) {
+export default function visitElement ( generator: DomGenerator, block: Block, state: State, node: Node ) {
 	if ( node.name in meta ) {
 		return meta[ node.name ]( generator, block, node );
 	}
@@ -54,8 +55,8 @@ export default function visitElement ( generator: DomGenerator, block: Block, st
 		let outro;
 
 		node.attributes
-			.sort( ( a, b ) => order[ a.type ] - order[ b.type ] )
-			.forEach( attribute => {
+			.sort( ( a: Node, b: Node ) => order[ a.type ] - order[ b.type ] )
+			.forEach( ( attribute: Node ) => {
 				if ( attribute.type === 'Transition' ) {
 					if ( attribute.intro ) intro = attribute;
 					if ( attribute.outro ) outro = attribute;
@@ -68,14 +69,14 @@ export default function visitElement ( generator: DomGenerator, block: Block, st
 		if ( intro || outro ) addTransitions( generator, block, childState, node, intro, outro );
 
 		if ( childState.allUsedContexts.length || childState.usesComponent ) {
-			const initialProps = [];
-			const updates = [];
+			const initialProps: string[] = [];
+			const updates: string[] = [];
 
 			if ( childState.usesComponent ) {
 				initialProps.push( `component: ${block.component}` );
 			}
 
-			childState.allUsedContexts.forEach( contextName => {
+			childState.allUsedContexts.forEach( ( contextName: string ) => {
 				if ( contextName === 'state' ) return;
 
 				const listName = block.listNames.get( contextName );
@@ -112,12 +113,12 @@ export default function visitElement ( generator: DomGenerator, block: Block, st
 	}
 
 	// special case – bound <option> without a value attribute
-	if ( node.name === 'option' && !node.attributes.find( attribute => attribute.type === 'Attribute' && attribute.name === 'value' ) ) { 	// TODO check it's bound
+	if ( node.name === 'option' && !node.attributes.find( ( attribute: Node ) => attribute.type === 'Attribute' && attribute.name === 'value' ) ) { 	// TODO check it's bound
 		const statement = `${name}.__value = ${name}.textContent;`;
 		node.initialUpdate = node.lateUpdate = statement;
 	}
 
-	node.children.forEach( child => {
+	node.children.forEach( ( child: Node ) => {
 		visit( generator, block, childState, child );
 	});
 
@@ -134,7 +135,7 @@ export default function visitElement ( generator: DomGenerator, block: Block, st
 	}
 }
 
-function getRenderStatement ( generator: DomGenerator, namespace, name ) {
+function getRenderStatement ( generator: DomGenerator, namespace: string, name: string ) {
 	if ( namespace === 'http://www.w3.org/2000/svg' ) {
 		return `${generator.helper( 'createSvgElement' )}( '${name}' )`;
 	}
diff --git a/src/generators/dom/visitors/Element/EventHandler.ts b/src/generators/dom/visitors/Element/EventHandler.ts
index 2189a45b2e..1bf9dda947 100644
--- a/src/generators/dom/visitors/Element/EventHandler.ts
+++ b/src/generators/dom/visitors/Element/EventHandler.ts
@@ -3,8 +3,9 @@ import flattenReference from '../../../../utils/flattenReference';
 import { DomGenerator } from '../../index';
 import Block from '../../Block';
 import { Node } from '../../../../interfaces';
+import { State } from '../../interfaces';
 
-export default function visitEventHandler ( generator: DomGenerator, block: Block, state, node: Node, attribute ) {
+export default function visitEventHandler ( generator: DomGenerator, block: Block, state: State, node: Node, attribute: Node ) {
 	const name = attribute.name;
 	const isCustomEvent = generator.events.has( name );
 	const shouldHoist = !isCustomEvent && state.inEachBlock;
@@ -20,8 +21,8 @@ export default function visitEventHandler ( generator: DomGenerator, block: Bloc
 	}
 
 	const context = shouldHoist ? null : state.parentNode;
-	const usedContexts = [];
-	attribute.expression.arguments.forEach( arg => {
+	const usedContexts: string[] = [];
+	attribute.expression.arguments.forEach( ( arg: Node ) => {
 		const { contexts } = block.contextualise( arg, context, true );
 
 		contexts.forEach( context => {
diff --git a/src/generators/dom/visitors/Element/Ref.ts b/src/generators/dom/visitors/Element/Ref.ts
index 8576f83eb5..10db528edf 100644
--- a/src/generators/dom/visitors/Element/Ref.ts
+++ b/src/generators/dom/visitors/Element/Ref.ts
@@ -2,8 +2,9 @@ import deindent from '../../../../utils/deindent.js';
 import { DomGenerator } from '../../index';
 import Block from '../../Block';
 import { Node } from '../../../../interfaces';
+import { State } from '../../interfaces';
 
-export default function visitRef ( generator: DomGenerator, block: Block, state, node: Node, attribute ) {
+export default function visitRef ( generator: DomGenerator, block: Block, state: State, node: Node, attribute: Node ) {
 	const name = attribute.name;
 
 	block.builders.create.addLine(
diff --git a/src/generators/dom/visitors/Element/addTransitions.ts b/src/generators/dom/visitors/Element/addTransitions.ts
index ea69a733af..80e02ad402 100644
--- a/src/generators/dom/visitors/Element/addTransitions.ts
+++ b/src/generators/dom/visitors/Element/addTransitions.ts
@@ -2,8 +2,9 @@ import deindent from '../../../../utils/deindent.js';
 import { DomGenerator } from '../../index';
 import Block from '../../Block';
 import { Node } from '../../../../interfaces';
+import { State } from '../../interfaces';
 
-export default function addTransitions ( generator: DomGenerator, block: Block, state, node: Node, intro, outro ) {
+export default function addTransitions ( generator: DomGenerator, block: Block, state: State, node: Node, intro, outro ) {
 	const wrapTransition = generator.helper( 'wrapTransition' );
 
 	if ( intro === outro ) {
diff --git a/src/generators/dom/visitors/IfBlock.ts b/src/generators/dom/visitors/IfBlock.ts
index 69c88f347d..a503c75361 100644
--- a/src/generators/dom/visitors/IfBlock.ts
+++ b/src/generators/dom/visitors/IfBlock.ts
@@ -3,6 +3,7 @@ import visit from '../visit';
 import { DomGenerator } from '../index';
 import Block from '../Block';
 import { Node } from '../../../interfaces';
+import { State } from '../interfaces';
 
 function isElseIf ( node: Node ) {
 	return node && node.children.length === 1 && node.children[0].type === 'IfBlock';
@@ -12,7 +13,7 @@ function isElseBranch ( branch ) {
 	return branch.block && !branch.condition;
 }
 
-function getBranches ( generator: DomGenerator, block: Block, state, node: Node ) {
+function getBranches ( generator: DomGenerator, block: Block, state: State, node: Node ) {
 	const branches = [{
 		condition: block.contextualise( node.expression ).snippet,
 		block: node._block.name,
@@ -44,13 +45,13 @@ function getBranches ( generator: DomGenerator, block: Block, state, node: Node
 	return branches;
 }
 
-function visitChildren ( generator: DomGenerator, block: Block, state, node: Node ) {
+function visitChildren ( generator: DomGenerator, block: Block, state: State, node: Node ) {
 	node.children.forEach( ( child: Node ) => {
 		visit( generator, node._block, node._state, child );
 	});
 }
 
-export default function visitIfBlock ( generator: DomGenerator, block: Block, state, node: Node ) {
+export default function visitIfBlock ( generator: DomGenerator, block: Block, state: State, node: Node ) {
 	const name = generator.getUniqueName( `if_block` );
 	const anchor = node.needsAnchor ? block.getUniqueName( `${name}_anchor` ) : ( node.next && node.next._state.name ) || 'null';
 	const params = block.params.join( ', ' );
@@ -82,7 +83,7 @@ export default function visitIfBlock ( generator: DomGenerator, block: Block, st
 	}
 }
 
-function simple ( generator: DomGenerator, block: Block, state, node: Node, branch, dynamic, { name, anchor, params, if_name } ) {
+function simple ( generator: DomGenerator, block: Block, state: State, node: Node, branch, dynamic, { name, anchor, params, if_name } ) {
 	block.builders.create.addBlock( deindent`
 		var ${name} = (${branch.condition}) && ${branch.block}( ${params}, ${block.component} );
 	` );
@@ -156,7 +157,7 @@ function simple ( generator: DomGenerator, block: Block, state, node: Node, bran
 	);
 }
 
-function compound ( generator: DomGenerator, block: Block, state, node: Node, branches, dynamic, { name, anchor, params, hasElse, if_name } ) {
+function compound ( generator: DomGenerator, block: Block, state: State, node: Node, branches, dynamic, { name, anchor, params, hasElse, if_name } ) {
 	const get_block = block.getUniqueName( `get_block` );
 	const current_block = block.getUniqueName( `current_block` );
 	const current_block_and = hasElse ? '' : `${current_block} && `;
@@ -212,7 +213,7 @@ function compound ( generator: DomGenerator, block: Block, state, node: Node, br
 
 // if any of the siblings have outros, we need to keep references to the blocks
 // (TODO does this only apply to bidi transitions?)
-function compoundWithOutros ( generator: DomGenerator, block: Block, state, node: Node, branches, dynamic, { name, anchor, params, hasElse } ) {
+function compoundWithOutros ( generator: DomGenerator, block: Block, state: State, node: Node, branches, dynamic, { name, anchor, params, hasElse } ) {
 	const get_block = block.getUniqueName( `get_block` );
 	const current_block_index = block.getUniqueName( `current_block_index` );
 	const previous_block_index = block.getUniqueName( `previous_block_index` );
diff --git a/src/generators/dom/visitors/MustacheTag.ts b/src/generators/dom/visitors/MustacheTag.ts
index 8118fd47ba..ed0f4c656b 100644
--- a/src/generators/dom/visitors/MustacheTag.ts
+++ b/src/generators/dom/visitors/MustacheTag.ts
@@ -2,8 +2,9 @@ import deindent from '../../../utils/deindent.js';
 import { DomGenerator } from '../index';
 import Block from '../Block';
 import { Node } from '../../../interfaces';
+import { State } from '../interfaces';
 
-export default function visitMustacheTag ( generator: DomGenerator, block: Block, state, node: Node ) {
+export default function visitMustacheTag ( generator: DomGenerator, block: Block, state: State, node: Node ) {
 	const name = node._state.name;
 	const value = block.getUniqueName( `${name}_value` );
 
diff --git a/src/generators/dom/visitors/RawMustacheTag.ts b/src/generators/dom/visitors/RawMustacheTag.ts
index 825f138d20..a66c71f938 100644
--- a/src/generators/dom/visitors/RawMustacheTag.ts
+++ b/src/generators/dom/visitors/RawMustacheTag.ts
@@ -2,8 +2,9 @@ import deindent from '../../../utils/deindent.js';
 import { DomGenerator } from '../index';
 import Block from '../Block';
 import { Node } from '../../../interfaces';
+import { State } from '../interfaces';
 
-export default function visitRawMustacheTag ( generator: DomGenerator, block: Block, state, node: Node ) {
+export default function visitRawMustacheTag ( generator: DomGenerator, block: Block, state: State, node: Node ) {
 	const name = node._state.basename;
 	const before = node._state.name;
 	const value = block.getUniqueName( `${name}_value` );
diff --git a/src/generators/dom/visitors/Text.ts b/src/generators/dom/visitors/Text.ts
index 67560a8721..d84ffefd68 100644
--- a/src/generators/dom/visitors/Text.ts
+++ b/src/generators/dom/visitors/Text.ts
@@ -1,8 +1,9 @@
 import { DomGenerator } from '../index';
 import Block from '../Block';
 import { Node } from '../../../interfaces';
+import { State } from '../interfaces';
 
-export default function visitText ( generator: DomGenerator, block: Block, state, node: Node ) {
+export default function visitText ( generator: DomGenerator, block: Block, state: State, node: Node ) {
 	if ( !node._state.shouldCreate ) return;
 	block.addElement( node._state.name, `${generator.helper( 'createText' )}( ${JSON.stringify( node.data )} )`, state.parentNode, node.usedAsAnchor );
 }
\ No newline at end of file
diff --git a/src/generators/dom/visitors/YieldTag.ts b/src/generators/dom/visitors/YieldTag.ts
index ebebb78557..1482c5dae5 100644
--- a/src/generators/dom/visitors/YieldTag.ts
+++ b/src/generators/dom/visitors/YieldTag.ts
@@ -1,7 +1,8 @@
 import { DomGenerator } from '../index';
 import Block from '../Block';
+import { State } from '../interfaces';
 
-export default function visitYieldTag ( generator: DomGenerator, block: Block, state ) {
+export default function visitYieldTag ( generator: DomGenerator, block: Block, state: State ) {
 	const parentNode = state.parentNode || block.target;
 
 	( state.parentNode ? block.builders.create : block.builders.mount ).addLine(
diff --git a/src/generators/server-side-rendering/index.ts b/src/generators/server-side-rendering/index.ts
index 657f598c67..7d53d018d8 100644
--- a/src/generators/server-side-rendering/index.ts
+++ b/src/generators/server-side-rendering/index.ts
@@ -2,20 +2,24 @@ import deindent from '../../utils/deindent.js';
 import Generator from '../Generator';
 import Block from './Block';
 import visit from './visit';
+import { Parsed, Node, CompileOptions } from '../../interfaces';
 
-class SsrGenerator extends Generator {
-	constructor ( parsed, source, name, options ) {
+export class SsrGenerator extends Generator {
+	bindings: string[];
+	renderCode: string;
+
+	constructor ( parsed: Parsed, source: string, name: string, options: CompileOptions ) {
 		super( parsed, source, name, options );
 		this.bindings = [];
 		this.renderCode = '';
 	}
 
-	append ( code ) {
+	append ( code: string ) {
 		this.renderCode += code;
 	}
 }
 
-export default function ssr ( parsed, source, options ) {
+export default function ssr ( parsed: Parsed, source: string, options: CompileOptions ) {
 	const format = options.format || 'cjs';
 	const name = options.name || 'SvelteComponent';
 
@@ -31,7 +35,7 @@ export default function ssr ( parsed, source, options ) {
 		conditions: []
 	});
 
-	parsed.html.children.forEach( node => {
+	parsed.html.children.forEach( ( node: Node ) => {
 		visit( generator, mainBlock, node );
 	});
 
diff --git a/src/index.ts b/src/index.ts
index b0fd1e7b30..95dd4e4591 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -48,7 +48,7 @@ export function compile ( source: string, _options: CompileOptions ) {
 	return compiler( parsed, source, options );
 }
 
-export function create ( source, _options = {} ) {
+export function create ( source: string, _options: CompileOptions ) {
 	_options.format = 'eval';
 
 	const compiled = compile( source, _options );
diff --git a/src/interfaces.ts b/src/interfaces.ts
index 0ffe275064..2a2d88e9e2 100644
--- a/src/interfaces.ts
+++ b/src/interfaces.ts
@@ -36,6 +36,7 @@ export interface CompileOptions {
 	format?: string;
 	name?: string;
 	filename?: string;
+	generate?: string;
 
 	dev?: boolean;
 	shared?: boolean | string;