extern type domain;
extern val domain : domain -> Domain => [Root];

extern type emailUser;
extern type email;

extern type aliasSource;
extern val userSource : emailUser -> aliasSource;
extern val defaultSource : aliasSource;
extern val catchAllSource : aliasSource;

extern type aliasTarget;
extern val addressTarget : email -> aliasTarget;
extern val addressesTarget : [email] -> aliasTarget;
extern val dropTarget : aliasTarget;

extern val aliasPrim : aliasSource -> aliasTarget -> [Domain];

val alias = \user -> \email -> aliasPrim (userSource user) (addressTarget email);
val aliasMulti = \user -> \emails -> aliasPrim (userSource user) (addressesTarget emails);
val aliasDrop = \user -> aliasPrim (userSource user) dropTarget;

val defaultAlias = \email -> aliasPrim defaultSource (addressTarget email);
val catchAllAlias = \email -> aliasPrim catchAllSource (addressTarget email);

domain "hcoop.net" with
	alias "schmeppo" "dlonker";
	aliasMulti "me" ["nowhere","smelly@yikes"];
	aliasDrop "yippo";

	defaultAlias "billy";
	catchAllAlias "bonkers"
end