This prepopulates the symbol table with our predefined "primitive" types
like mu/container, mu/gateway, mu/func, and the like. Also added a positive
test case to ensure the full set works; this will obviously need updating as
we embellish the predefined types with things like required parameters.
This change adds rudimentary type binding to phase 2 of the binder. Note that
we still don't have the notion of predefined types (for the primitives), so this
basically rejects any well-formed Mufile. Primitives are on deck.
Instead of:
name: mystack
public:
someservice
private:
someotherservice
we want it to be:
name: mystack
services:
public:
someservice
private
someotherservice
I had always intended it to be this way, but coded up the ASTs wrong.
Neither the YAML nor JSON decoders appreciate having pointers in the AST
structures. This is unfortunate because we end up mutating them later on.
Perhaps we will need separate parse trees and ASTs after all ...
This change lays some groundwork that registers symbols when doing semantic
analysis of the resulting AST. For now, that just entails detecting duplicate
services by way of symbol registration.
Note that we've also split binding into two phases to account for the fact
that intra-stack dependencies are wholly legal.
