Nostrのフィルターを表す型の値からSQLのwhere句の部分の文字列を構成するところまでできた。次の感じ。 ghci> showSqlWhere FltJsn.null { Filter.tags = [('a', ["foo", "bar"]), ('A', ["bar"])] } ("(((((true) AND (true)) AND (true)) AND (((tags_a.value = ?) OR ((tags_a.value = ?) OR (false))) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND (((tags_ua.value = ?) OR (false)) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND ((true) AND (true)))))))))))))))))))))))))))))))))))))))))))))))))))))) AND (true)) AND (true)",[VText "foo",VText "bar",VText "bar"]) AND (true) AND (true) ...みたいになってるのは指定されていない「一文字タグ」について全部trueを置いているから。 ?になっている部分にタプルの第二要素のVText "foo"とかの値が入る感じ。