whl
' ( arg$:?command
  & ( get'db
    | (db=1)&lst$(db,db,NEW)
    )
  &   !command
    : (   add
        & :?name:?tag:?date
        &   whl
          ' ( arg$:?argmnt
            & arg$:?value
            &   (!argmnt.!value)
              : ( (title|name.?name)
                | (category|tag.?tag)
                | (date.?date)
                )
            )
        & (   !name:~
            & !tag:~
            & !date:~
            & (   !db:?*!tag^(?+(!date.!name)+?)*?
                & out$"This record already exists"
              |   !tag^(!date.!name)*!db:?db
                & lst$(db,db,NEW)
              )
          | out$"invalid data"
          )
      |   latest
        & :?date
        & nothing found:?latest
        & (   !db
            :   ?
              *   ?tag
                ^ ( ?
                  + ( (>!date:?date.?name)
                    & (!name,!tag,!date):?latest
                    & ~
                    )
                  + ?
                  )
              * ?
          | out$!latest
          )
      |   latest/category
        & :?date:?latests:?latest
        & (   !db
            :   ?
              *   ( ?tag
                  & !latests !latest:?latests
                  & :?latest:?date
                  )
                ^ ( ?
                  + ( (>!date:?date.?name)
                    & (!name,!tag,!date):?latest
                    & ~
                    )
                  + ?
                  )
              * ?
          | !latests !latest:?latests&out$!latests
          )
      |   sorted
        & 0:?sorted
        & (   !db
            :   ?
              *   ?tag
                ^ ( ?
                  + ( (?date.?name)
                    & (!date.!name,!tag,!date)+!sorted:?sorted
                    & ~
                    )
                  + ?
                  )
              * ?
          |   whl
            ' (!sorted:(?.?row)+?sorted&out$!row)
          )
      )
  );