2.8.7 Compilation unit productions

Compilation = [UNSAFE] (Interface | Module) | GenInf | GenMod.

Interface   = INTERFACE Id ";" {Import} {Decl} END Id "."
            | INTERFACE Id "=" Id GenActls END Id ".".
Module      = MODULE Id [EXPORTS IdList] ";" {Import} Block Id "."
            | MODULE Id [EXPORTS IdList] "=" Id GenActls END Id ".".

GenInf = GENERIC INTERFACE Id GenFmls ";" {Import} {Decl} END Id ".".
GenMod = GENERIC MODULE Id GenFmls ";" {Import} Block Id ".".

Import      = AsImport | FromImport.
AsImport    = IMPORT ImportItem {"," ImportItem} ";".
FromImport  = FROM Id IMPORT IdList ";".
Block       = {Decl} BEGIN S END.
Decl = CONST {ConstDecl ";"}
     | TYPE {TypeDecl ";"}
     | EXCEPTION {ExceptionDecl ";"}
     | VAR {VariableDecl ";"}
     | ProcedureHead ["=" Block Id] ";"
     | REVEAL {QualId ("=" | "<:") Type ";"}.

GenFmls        = "(" [IdList] ")".
GenActls       = "(" [IdList] ")".
ImportItem     = Id | Id AS Id.
ConstDecl      = Id [":" Type] "=" ConstExpr.
TypeDecl       = Id ("=" | "<:") Type.
ExceptionDecl  = Id ["(" Type ")"].
VariableDecl   = IdList (":" Type & ":=" Expr).
ProcedureHead  = PROCEDURE Id Signature.

Signature      = "(" Formals ")" [":" Type] [RAISES Raises].
Formals        = [ Formal {";" Formal} [";"] ].
Formal         = [Mode] IdList (":" Type & ":=" ConstExpr).
Mode           = VALUE | VAR | READONLY.
Raises         = "{" [ QualId {"," QualId} ] "}" | ANY.