As per #774 this PR takes us a couple more steps towards not having a 'root' predicate.
interfaces are now in Contract.
top_level_symbols are now just symbols and have been wrapped in a struct. The plan is to have an instance in Contract for all actual top-level symbols, and each predicate would have their own symbols which may not shadow the top-levels, but won't clash with other predicates. TBC.
Expr::PathByKey is gone, now we just have Expr::PathByName which is renamed to Expr::Path. This removes the dependency between Expr (a globally used struct) and VarKey (only significant in predicates). As a consequence there is now also no dependency between Type and predicates.
Add DisplayWithContract which is the same as DisplayWithPred except just for contract contexts (like displaying Expr and Type). This has simplified a bunch of code which needed a predicate just to generate a Display string, especially places like the type checker and its error messages, and has reduced the need for using Contract::root_pred() just as a stand-in for DisplayWithPred.
We're not quite there but I think pretty close to removing the 'root' predicate which will simplify things further.
As per #774 this PR takes us a couple more steps towards not having a 'root' predicate.
interfacesare now inContract.top_level_symbolsare now justsymbolsand have been wrapped in a struct. The plan is to have an instance inContractfor all actual top-level symbols, and each predicate would have their ownsymbolswhich may not shadow the top-levels, but won't clash with other predicates. TBC.Expr::PathByKeyis gone, now we just haveExpr::PathByNamewhich is renamed toExpr::Path. This removes the dependency betweenExpr(a globally used struct) andVarKey(only significant in predicates). As a consequence there is now also no dependency betweenTypeand predicates.DisplayWithContractwhich is the same asDisplayWithPredexcept just for contract contexts (like displayingExprandType). This has simplified a bunch of code which needed a predicate just to generate aDisplaystring, especially places like the type checker and its error messages, and has reduced the need for usingContract::root_pred()just as a stand-in forDisplayWithPred.We're not quite there but I think pretty close to removing the 'root' predicate which will simplify things further.