Factor/Dispatch ideas

A generic approach to handle generic methods, aka polymorphic calls, aka dynamic binding.

First, we can conceptually divide this operation into three primitive operations:

1. computing the value
2. signature->word lookup
3. execute the word

1. Computing the signature

This a simple way to generalize single dispatch, subjective dispatch, multiple dispatch and predicate dispatch.

Examples:

• Single dispatch signature: [ drop drop class ]
• Multiple dispatch signature: [ [ class ] tri@ ]
• Subjective dispatch signature: [ access get ]
• Predicate dispatch signature: [ 0 > ]