Well, my point is not that multi-language code editor must provide semantic information for every language it can edit (that's just infeasible), but that editor's core must be designed with semantics in mind.
I.e., not "well, it's text and core has no idea what it is but plugins are free to do anything with that", but "well, core has no idea what that 'typeclass' thingy code analyzer says it is, but it's happy to keep track of it and provide standard interfaces to use this info so maybe highlighter or code folding parts would figure out how to use that information"
Then you could start with regexp mess-based parser that provides very basic understanding of the code and replace it with something that gives better code insight at later time, without rewriting the rest. And have generic refactoring module that can operate on many languages just by knowing about names and their possible scopes (whatever scoping type language is, in common cases I believe that still could be reduced to "in this text region").
I've heard LightTable is doing something like this, but never had a time to properly evaluate it and see for myself.
Also, JetBrains' IDEs (IntelliJ IDEA, PyCharm, etc.) are notorious to have good understanding of code semantics, both out of the box and through plugin system.
I.e., not "well, it's text and core has no idea what it is but plugins are free to do anything with that", but "well, core has no idea what that 'typeclass' thingy code analyzer says it is, but it's happy to keep track of it and provide standard interfaces to use this info so maybe highlighter or code folding parts would figure out how to use that information"
Then you could start with regexp mess-based parser that provides very basic understanding of the code and replace it with something that gives better code insight at later time, without rewriting the rest. And have generic refactoring module that can operate on many languages just by knowing about names and their possible scopes (whatever scoping type language is, in common cases I believe that still could be reduced to "in this text region").