Validation of input array types

[clord]

Toml requires arrays to be monomorphic lists. Since we parse to an ADT, we'll have to zip through lists and validate they are all the same type. GADTs might work too?

[pbrisbin]

AFAICT this is happening: https://github.com/pliosoft/toml-parse/blob/master/src/Text/Toml/Parser.hs#L84