%- tydecl case = Nominative | Accusative | Dative | Genitive | Instrumental tydecl gender = Masculine | Feminine | Neuter tydecl number = Singular | Plural ; demonstrative pronouns ; "this" or "these" (:def decline (:lambda x (case, gender, number) (:match x [((Nominative|Accusative), _, Plural) "þas"] [((Nominative|Accusative), Neuter, Singular) "þis"] [((Genitive|Dative|Instrumental), Feminine, Plural) "þisse"] [(Dative, (Masculine|Neuter), Singular) "þissum"] )))