Interpreting a CFG derivation as a string in Japanese. That is, we generate a yield of a CFG derivation, this time in Japanese.
We represent each node in the derivation tree by a Japanese phrase or a Japanese sentential form (that is, a phrase with holes). Contrast with the EN interpreter in CFG.hs
A verb or a verb-like word (e.g., an i-adjective) require arguments of particular cases. We need a way for a verb to specify the desired case of its arguments.
The type family TJ defines the types of sentential forms corresponding to syntactic categories.
As we shall see in QCFGJ.hs, we are going to need high (raised) types of our NP. A verb will ask its argument to turn itself to the desired case.