data Module
  | Module "module" uident "{" ExportDList ImportDList TypeDList InstDList VarDList "}"

data ExportD
  | TypeEx "export" uident
  | VarEx "export" lident

data ImportD | ImportD "import" uident AsSpec

data AsSpec
  | AsAS "as" uident
  | EmptyAS 

data TypeD | TypeD "type" uident VarList "=" TyDecl
data VarD | VarD lident DeclSym Exp
data InstD | InstD "instance" uident Type

data DeclSym
  | Macro "=>"
  | Define "="

data TyDecl
  | TyRecord "record" "{" FieldTList "}"
  | TyTagged "tagged" ConCList
  | TyEnum "enum" EnumCList
  | TySyn "synonym" Type
  | TyNewtype "newtype" uident Type
  | TyUnit "unit" uident

data Exp
  | LetE "let" lident DeclSym Exp "in" Exp
  | LamE "\\" lident "->" Exp
  | SwitchE "switch" Exp "of" Default "{" SwitchAltList "}"
  | AppE "(" Exp Exp ")"
  | AscribeE "(" Exp "::" Type ")"
  | VarE lident
  | LitE Lit

data Default
  | DefaultNone
  | DefaultSome Exp

data Lit
  | CharL char
  | StringL string
  | NmbrL number

data Type
  | TyCxt "{" CxtList "}" "=>" Type
  | TyFun "(" Type "->" Type ")"
  | TyVoid "VoidT"
  | TyConstr "(" uident TypeList ")"
  | TyVarT lident

data SwitchAlt | SwitchAlt Exp "->" Exp

data Cxt | Cxt uident VarList

data ConC | ConC uident Type

data EnumC | EnumC uident

data FieldT | FieldT uident "::" Type

data Var | Var lident

list ExportDList ExportD empty terminator ";" vert
list ImportDList ImportD empty terminator ";" vert
list VarDList VarD empty terminator ";" vert
list TypeDList TypeD empty terminator ";" vert
list InstDList InstD empty terminator ";" vert
list SwitchAltList SwitchAlt empty terminator ";" vert
list EnumCList EnumC nonempty separator "|" horiz
list ConCList ConC nonempty separator "|" horiz
list FieldTList FieldT nonempty separator "," horiz
list VarList Var empty separator "" horiz
list TypeList Type empty separator "" horiz
list CxtList Cxt nonempty separator "," horiz