TypedSeparatedFile is not what makes something a TypedTsv. If you have this, what you will have is a DailySuffixSource which has an apply method which will create TypedTsv's. ie

(DailySuffixTypedTsv("prefix))("input) would be a TypedTsv. This is obviously not what you want. Waht you want is the thing that TypedSeparatedFile creates, a TypedDelimited

See: https://github.com/twitter/scalding/blob/klin_suffix_typedtsv/scalding-core/src/main/scala/com/twitter/scalding/TypedDelimited.scala?pr=%2Ftwitter%2Fscalding%2Fpull%2F873#L94

Does this make sense? TypedSeparatedFile is something which the TypedTsv, TypedCsv object etc extend for ease of the creation of various TypedDelimited. TypedDelimited is what makes something a TypedTsv. It's a little confusing I understand.