diff --git a/src/ast-spec.ts b/src/ast-spec.ts
new file mode 100644
index 000000000..fe99552fc
--- /dev/null
+++ b/src/ast-spec.ts
@@ -0,0 +1,567 @@
+
+import { Value } from "./evaluator"
+import { Package } from "./package"
+
+export class Syntax {
+
+}
+
+export interface EndOfFile extends BoltToken, JSToken {}
+
+export interface Token {}
+export interface SourceFile {}
+export interface FunctionBodyElement {}
+export interface ReturnStatement {}
+
+// Bolt language AST definitions
+
+export interface BoltSyntax {}
+
+export interface BoltToken extends Token, BoltSyntax {}
+
+export interface BoltStringLiteral extends BoltToken {
+  value: String,
+}
+
+export interface BoltIntegerLiteral extends BoltToken {
+  value: bigint,
+}
+
+export interface BoltSymbol extends BoltToken {}
+
+export interface BoltIdentifier extends BoltSymbol {
+  text: String,
+}
+
+export interface BoltOperatorLike extends BoltSymbol {}
+
+export interface BoltOperator extends BoltSymbol {
+  text: String,
+}
+
+export interface BoltAssignment extends BoltToken {
+  operator: String | null,
+}
+
+export interface BoltComma      extends BoltToken {}
+export interface BoltSemi       extends BoltToken {}
+export interface BoltColon      extends BoltToken {}
+export interface BoltColonColon extends BoltToken {}
+export interface BoltDot        extends BoltToken {}
+export interface BoltDotDot     extends BoltToken {}
+export interface BoltRArrow     extends BoltToken {}
+export interface BoltRArrowAlt  extends BoltToken {}
+export interface BoltLArrow     extends BoltToken {}
+export interface BoltEqSign     extends BoltToken {}
+
+export interface BoltGtSign    extends BoltToken, BoltOperatorLike {}
+export interface BoltExMark    extends BoltToken, BoltOperatorLike {}
+export interface BoltLtSign    extends BoltToken, BoltOperatorLike {}
+export interface BoltVBar      extends BoltToken, BoltOperatorLike {}
+
+export interface BoltKeyword {}
+
+export interface BoltWhereKeyword   extends BoltToken, BoltKeyword {}
+export interface BoltQuoteKeyword   extends BoltToken, BoltKeyword {}
+export interface BoltFnKeyword      extends BoltToken, BoltKeyword {}
+export interface BoltForeignKeyword extends BoltToken, BoltKeyword {}
+export interface BoltForKeyword     extends BoltToken, BoltKeyword {}
+export interface BoltLetKeyword     extends BoltToken, BoltKeyword {}
+export interface BoltReturnKeyword  extends BoltToken, BoltKeyword {}
+export interface BoltLoopKeyword    extends BoltToken, BoltKeyword {}
+export interface BoltYieldKeyword   extends BoltToken, BoltKeyword {}
+export interface BoltMatchKeyword   extends BoltToken, BoltKeyword {}
+export interface BoltImportKeyword  extends BoltToken, BoltKeyword {}
+export interface BoltExportKeyword  extends BoltToken, BoltKeyword {}
+export interface BoltPubKeyword     extends BoltToken, BoltKeyword {}
+export interface BoltModKeyword     extends BoltToken, BoltKeyword {}
+export interface BoltMutKeyword     extends BoltToken, BoltKeyword {}
+export interface BoltEnumKeyword    extends BoltToken, BoltKeyword {}
+export interface BoltStructKeyword  extends BoltToken, BoltKeyword {}
+export interface BoltTypeKeyword    extends BoltToken, BoltKeyword {}
+export interface BoltTraitKeyword   extends BoltToken, BoltKeyword {}
+export interface BoltImplKeyword    extends BoltToken, BoltKeyword {}
+
+export interface BoltPunctuated extends BoltToken {
+  text: String,
+}
+
+export interface BoltParenthesized extends BoltPunctuated {}
+export interface BoltBraced extends BoltPunctuated {}
+export interface BoltBracketed extends BoltPunctuated {}
+
+export interface BoltSourceFile extends BoltSyntax, SourceFile {
+  elements: BoltSourceElement[],
+  pkg: Package,
+}
+
+export interface BoltQualName extends BoltSyntax {
+  isAbsolute: boolean,
+  modulePath: BoltIdentifier[],
+  name: BoltSymbol,
+}
+
+export interface BoltTypeExpression extends BoltSyntax {}
+
+export interface BoltTypeOfExpression extends BoltTypeExpression {
+  expression: BoltExpression,
+}
+
+export interface BoltReferenceTypeExpression extends BoltTypeExpression {
+  name: BoltQualName,
+  typeArgs: BoltTypeExpression[] | null,
+}
+
+export interface BoltFunctionTypeExpression extends BoltTypeExpression {
+  params: BoltParameter[],
+  returnType: BoltTypeExpression | null,
+}
+
+export interface BoltLiftedTypeExpression extends BoltTypeExpression {
+  expression: BoltExpression, 
+}
+
+export interface BoltTypeParameter extends BoltSyntax {
+  index: number,
+  name: BoltIdentifier,
+  typeExpr: BoltTypeExpression | null,
+  defaultType: BoltTypeExpression | null,
+}
+
+export interface BoltPattern extends BoltSyntax {}
+
+export interface BoltBindPattern extends BoltPattern {
+  name: BoltIdentifier,
+}
+
+export interface BoltTypePattern extends BoltPattern {
+  typeExpr: BoltTypeExpression,
+  nestedPattern: BoltPattern,
+}
+
+export interface BoltExpressionPattern extends BoltPattern {
+  expression: BoltExpression,
+}
+
+export interface BoltTuplePatternElement extends BoltSyntax {
+  index: number,
+  pattern: BoltPattern,
+}
+
+export interface BoltTuplePattern extends BoltPattern {
+  elements: BoltTuplePatternElement[],
+}
+
+export interface BoltRecordFieldPattern extends BoltSyntax {
+  isRest: boolean,
+  name: BoltIdentifier | null,
+  pattern: BoltPattern | null,
+}
+
+export interface BoltRecordPattern extends BoltPattern {
+  name: BoltTypeExpression,
+  fields: BoltRecordFieldPattern[],
+}
+
+export interface BoltExpression extends BoltSyntax {}
+
+export interface BoltQuoteExpression extends BoltExpression {
+  tokens: (Token | BoltExpression)[],
+}
+
+export interface BoltTupleExpression extends BoltExpression {
+  elements: BoltExpression[],
+}
+
+export interface BoltReferenceExpression extends BoltExpression {
+  name: BoltQualName,
+}
+
+export interface BoltMemberExpression extends BoltExpression {
+  expression: BoltExpression,
+  path: BoltIdentifier[],
+}
+
+export interface BoltFunctionExpression extends BoltExpression {
+  params: BoltParameter[],
+  returnType: BoltTypeExpression | null,
+  body: BoltFunctionBodyElement[],
+}
+
+export interface BoltCallExpression extends BoltExpression {
+  operator: BoltExpression,
+  operands: BoltExpression[],
+}
+
+export interface BoltYieldExpression extends BoltExpression {
+  value: BoltExpression,
+}
+
+export interface BoltMatchArm extends BoltSyntax {
+  pattern: BoltPattern,
+  body: BoltExpression,
+}
+
+export interface BoltMatchExpression extends BoltExpression {
+  value: BoltExpression,
+  arms: BoltMatchArm[],
+}
+
+export interface BoltCase extends BoltSyntax {
+  test: BoltExpression,
+  result: BoltExpression,
+}
+
+export interface BoltCaseExpression extends BoltExpression {
+  cases: BoltCase[],
+}
+
+export interface BoltBlockExpression extends BoltExpression {
+  elements: BoltFunctionBodyElement[],
+}
+
+export interface BoltConstantExpression extends BoltExpression {
+  value: Value,
+}
+
+export interface BoltStatement extends BoltSyntax, BoltFunctionBodyElement, BoltSourceElement {}
+
+export interface BoltReturnStatement extends ReturnStatement, BoltStatement {
+  value: BoltExpression | null,
+}
+
+export interface BoltConditionalCase extends BoltSyntax {
+  test: BoltExpression | null,
+  body: BoltFunctionBodyElement[],
+}
+
+export interface BoltConditionalStatement extends BoltStatement {
+  cases: BoltConditionalCase[],
+}
+
+export interface BoltResumeStatement extends BoltStatement {
+  value: BoltExpression,
+}
+
+export interface BoltExpressionStatement extends BoltStatement {
+  expression: BoltExpression,
+}
+
+export interface BoltLoopStatement extends BoltStatement {
+  elements: BoltFunctionBodyElement[],
+}
+
+export interface BoltParameter extends BoltSyntax {
+  index: number,
+  bindings: BoltPattern,
+  typeExpr: BoltTypeExpression | null,
+  defaultValue: BoltExpression | null,
+}
+
+export interface BoltDeclaration extends BoltSyntax, BoltSourceElement {}
+
+export interface BoltTypeDeclaration extends BoltSyntax, BoltSourceElement {}
+
+enum BoltModifiers {
+  IsMutable   = 0x1,
+  IsPublic    = 0x2,
+}
+
+export interface BoltModule extends BoltSyntax, BoltSourceElement {
+  modifiers: BoltModifiers,
+  name: BoltIdentifier[],
+  elements: BoltSourceElement[],
+}
+
+export interface BoltDeclarationLike {}
+
+export interface BoltFunctionBodyElement extends FunctionBodyElement {}
+
+export interface BoltFunctionDeclaration extends BoltFunctionBodyElement, BoltDeclaration, BoltDeclarationLike, BoltTraitOrImplElement {
+  modifiers: BoltModifiers,
+  target: String,
+  name: BoltSymbol,
+  params: BoltParameter[],
+  returnType: BoltTypeExpression | null,
+  typeParams: BoltTypeParameter[] | null,
+  body: BoltFunctionBodyElement[],
+}
+
+export interface BoltVariableDeclaration extends BoltFunctionBodyElement, BoltDeclaration, BoltDeclarationLike {
+  modifiers: BoltModifiers,
+  bindings: BoltPattern,
+  typeExpr: BoltTypeExpression | null,
+  value: BoltExpression | null,
+}
+
+export interface BoltImportSymbol extends BoltSyntax {}
+
+export interface BoltPlainImportSymbol extends BoltImportSymbol {
+  remote: BoltQualName,
+  local: BoltSymbol,
+}
+
+export interface BoltImportDirective extends BoltSyntax, BoltSourceElement {
+  modifiers: BoltModifiers,
+  file: BoltStringLiteral,
+  symbols: BoltImportSymbol[] | null,
+}
+
+export interface BoltExportSymbol extends BoltSyntax {}
+
+export interface BoltPlainExportSymbol extends BoltExportSymbol {
+  local: BoltQualName,
+  remote: BoltSymbol,
+}
+
+export interface BoltExportDirective extends BoltSourceElement {
+  file: String,
+  symbols: BoltExportSymbol[] | null,
+}
+
+export interface BoltTraitOrImplElement {}
+
+export interface BoltTraitDeclaration extends BoltDeclarationLike, BoltTypeDeclaration {
+  modifiers: BoltModifiers,
+  typeParams: BoltTypeParameter[] | null,
+  name: BoltIdentifier,
+  typeBoundExpr: BoltTypeExpression | null,
+  elements: BoltTraitOrImplElement[] | null,
+}
+
+export interface BoltImplDeclaration extends BoltTypeDeclaration, BoltDeclarationLike {
+  modifiers: BoltModifiers,
+  typeParams: BoltTypeParameter[] | null,
+  name: BoltIdentifier,
+  traitTypeExpr: BoltTypeExpression | null,
+  elements: BoltTraitOrImplElement[],
+}
+
+export interface BoltTypeAliasDeclaration extends BoltDeclarationLike, BoltTypeDeclaration, BoltTraitOrImplElement {
+  modifiers: BoltModifiers,
+  name: BoltIdentifier,
+  typeParams: BoltTypeParameter[] | null,
+  typeExpr: BoltTypeExpression,
+}
+
+export interface BoltRecordMember extends BoltSyntax {}
+
+export interface BoltRecordField extends BoltRecordMember {
+  name: BoltIdentifier,
+  typeExpr: BoltTypeExpression,
+}
+
+export interface BoltRecordDeclaration extends BoltDeclaration, BoltTypeDeclaration, BoltDeclarationLike {
+  modifiers: BoltModifiers,
+  name: BoltIdentifier,
+  typeParms: BoltTypeParameter[] | null,
+  members: BoltRecordMember[] | null,
+}
+
+export interface BoltSourceElement {}
+
+export interface BoltMacroCall extends BoltRecordMember, BoltSourceElement, BoltTraitOrImplElement, BoltFunctionBodyElement {
+  name: BoltIdentifier,
+  text: String,
+}
+
+// JavaScript AST definitions
+
+export interface JSSyntax {}
+
+export interface JSToken extends JSSyntax, Token {}
+
+export interface JSIdentifier extends JSToken {
+  text: String,
+}
+
+export interface JSString extends JSToken {
+  value: String,
+}
+
+export interface JSInteger extends JSToken {
+  value: bigint,
+}
+
+export interface JSFromKeyword extends JSToken {}
+export interface JSReturnKeyword extends JSToken {}
+export interface JSTryKeyword extends JSToken {}
+export interface JSFinallyKeyword extends JSToken {}
+export interface JSCatchKeyword extends JSToken {}
+export interface JSImportKeyword extends JSToken {}
+export interface JSAsKeyword extends JSToken {}
+export interface JSConstKeyword extends JSToken {}
+export interface JSLetKeyword extends JSToken {}
+export interface JSExportKeyword extends JSToken {}
+export interface JSFunctionKeyword extends JSToken {}
+export interface JSWhileKeyword extends JSToken {}
+export interface JSForKeyword extends JSToken {}
+
+export interface JSOperatorLike {}
+
+export interface JSOperator extends JSToken {
+  text: String,
+}
+
+export interface JSCloseBrace extends JSToken {}
+export interface JSCloseBracket extends JSToken {}
+export interface JSCloseParen extends JSToken {}
+export interface JSOpenBrace extends JSToken {}
+export interface JSOpenBracket extends JSToken {}
+export interface JSOpenParen extends JSToken {}
+export interface JSSemi extends JSToken {}
+export interface JSComma extends JSToken {}
+export interface JSDot extends JSToken {}
+export interface JSDotDotDot extends JSToken {}
+export interface JSMulOp extends JSToken, JSOperatorLike {}
+export interface JSAddOp extends JSToken, JSOperatorLike {}
+export interface JSDivOp extends JSToken, JSOperatorLike {}
+export interface JSSubOp extends JSToken, JSOperatorLike {}
+export interface JSLtOp extends JSToken, JSOperatorLike {}
+export interface JSGtOp extends JSToken, JSOperatorLike {}
+export interface JSBOrOp extends JSToken, JSOperatorLike {}
+export interface JSBXorOp extends JSToken, JSOperatorLike {}
+export interface JSBAndOp extends JSToken, JSOperatorLike {}
+export interface JSBNotOp extends JSToken, JSOperatorLike {}
+export interface JSNotOp extends JSToken, JSOperatorLike {}
+
+export interface JSPattern extends JSSyntax {}
+
+export interface JSBindPattern extends JSPattern {
+  name: JSIdentifier,
+}
+
+export interface JSExpression extends JSSyntax {}
+
+export interface JSConstantExpression extends JSExpression {
+  value: Value,
+}
+
+export interface JSMemberExpression extends JSExpression {
+  value: JSExpression,
+  property: JSIdentifier,
+}
+
+export interface JSCallExpression extends JSExpression {
+  operator: JSExpression,
+  operands: JSExpression[],
+}
+
+export interface JSBinaryExpression extends JSExpression {
+  left: JSExpression,
+  operator: JSOperator,
+  right: JSExpression,
+}
+
+export interface JSUnaryExpression extends JSExpression {
+  operator: JSOperator,
+  operand: JSExpression
+}
+
+export interface JSNewExpression extends JSExpression {
+  target: JSExpression,
+  args: JSExpression[],
+}
+
+export interface JSSequenceExpression extends JSExpression {
+  expressions: JSExpression[],
+}
+
+export interface JSConditionalExpression extends JSExpression {
+  test: JSExpression,
+  consequent: JSExpression,
+  alternate: JSExpression,
+}
+
+export interface JSLiteralExpression extends JSExpression {
+  value: Value,
+}
+
+export interface JSReferenceExpression extends JSExpression {
+  name: String,
+}
+
+export interface JSSourceElement {}
+
+export interface JSFunctionBodyElement extends FunctionBodyElement {}
+
+export interface JSStatement extends JSSyntax, JSSourceElement, JSFunctionBodyElement {}
+
+export interface JSCatchBlock extends JSSyntax {
+  bindings: JSPattern | null,
+  elements: JSSourceElement[],
+}
+
+export interface JSTryCatchStatement extends JSStatement {
+  tryBlock: JSSourceElement[],
+  catchBlock: JSCatchBlock | null,
+  finalBlock: JSSourceElement[] | null,
+}
+
+export interface JSExpressionStatement extends JSStatement {
+  expression: JSExpression,
+}
+
+export interface JSConditionalCase extends JSSyntax {
+  test: JSExpression | null,
+  body: JSFunctionBodyElement[],
+}
+
+export interface JSConditionalStatement extends JSStatement {
+  cases: JSConditionalCase[],
+}
+
+export interface JSReturnStatement extends ReturnStatement, JSStatement {
+  value: JSExpression | null,
+}
+
+export interface JSParameter extends JSSyntax {
+  index: number,
+  bindings: JSPattern,
+  defaultValue: JSExpression | null,
+}
+
+export interface JSDeclaration extends JSSyntax, JSSourceElement {}
+
+enum JSDeclarationModifiers {
+  IsExported = 0x1,
+}
+
+export interface JSImportBinding extends JSSyntax {}
+
+export interface JSImportStarBinding extends JSImportBinding {
+  local: JSIdentifier,
+}
+
+export interface JSImportAsBinding extends JSImportBinding {
+  remote: JSIdentifier,
+  local: JSIdentifier | null,
+}
+
+// By exception, we alloww 'import ..'-statements to appear in foreign function bodies
+export interface JSImportDeclaration extends JSDeclaration, JSFunctionBodyElement {
+  bindings: JSImportBinding[],
+  filename: JSString,
+}
+
+export interface JSFunctionDeclaration extends JSDeclaration, JSFunctionBodyElement {
+  modifiers: JSDeclarationModifiers,
+  name: JSIdentifier,
+  params: JSParameter[],
+  body: JSStatement[],
+}
+
+export interface JSArrowFunctionDeclaration extends JSDeclaration, JSFunctionBodyElement {
+  name: JSIdentifier,
+  params: JSParameter[],
+  body: JSExpression,
+}
+
+export interface JSLetDeclaration extends JSDeclaration, JSFunctionBodyElement {
+  bindings: JSPattern,
+  value: JSExpression | null,
+}
+
+export interface JSSourceFile extends JSSyntax, SourceFile {
+  elements: JSSourceElement[],
+}