Force hash keys/values to be particular types?

[tfausak]

For hashes with strip: false, it might be useful to specify the types of the keys and/or values. For example:

hash :hash,
  strip: false,
  keys: Symbol,
  values: Integer

[tfausak]

I think we should support this. Except instead of specifying a class (Symbol), it should behave more like an array and accept a filter (:symbol or symbol).

[tfausak]

It won't be possible to use the DSL to describe keys or values. They'll have to be symbols.

hash :hash,
  strip: false,
  keys: :symbol,
  values: :integer

I'm less sure now about supporting this. Should it only be allowed if strip is false? How should explicitly defined filters be handled?

hash :useless,
  keys: :symbol
hash :confusing,
  keys: :integer,
  values: :integer do
    boolean :what_am_i
  end