Partial didn't really work, might not be needed

Consider a function with four parameters: you give partial a pair,
partial is applied to a pair, but the inner function gets a pair of
pairs, not a “proper list”. We could add something within the body of
partial to fix this, but do we actually need a notion of partial
application with SNF? I think we can just factor out the partial
application as a word, but I’ll have to look more closely.