declarations ::= <declaration> <declarations>
declaration ::= <enum_decl> | <struct_decl> | <type_decl> | <protocol_decl>

type_decl ::= "type" <ident> <ident> ";"

enum_decl ::= "enum" <ident> "{" "}" 
            | "enum" <ident> "{" <enum_members> "}"


enum_members ::= <enum_member> ["," <enum_member>]+ [","]

enum_member ::= <ident> "=" <number>


struct_decl ::= "struct" <ident> "{" "}"
              | "struct" <ident> "{" <struct_members> "}"

struct_members ::= <struct_member>
                 | <struct_member> ","
                 | <struct_member> "," <struct_members> 
				 | <struct_member> "," <struct_members>

protocol_decl ::= "protocol" <ident> "{" "}"
                | "protocol" <ident> "{" <protocol_member>+ "}"

protocol_member ::= "fn" <ident>"("[<arg_list>]")" "->" <ident> ";"

arg_list ::= <ident> ["," <ident>]+