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The problem is much easier (at least 10x easier) for a dynamic language with a REPL or playground environment (scratch in Emacs) than it is with a static language, or providing stateless insight based on cursor location rather than the set of forms you've evaluated. With a REPL or playground, you've got all the libraries loaded, all the function definitions in a map in your interpreter, and if you have a partial identifier you can simply do a prefix search in the interpreter. The interpreter is live; define a new function, and it's added to the map, so it's available for subsequent completions. If the function definition is wrong, hey, it's a REPL, next line try again please. In a stateless situation, or for a static language, you need to build that map. Ideally you use the compiler's front end, but then the front end needs to be hardened to recover properly from errors. It needs to be told about the cursor location, and when it hits the cursor location in the middle of an incomplete symbol, it needs to figure out what's appropriate to complete at that point based on the stack of scopes available, and jump back out to the editor (or use coroutines, or pause its thread, or whatever) with what it found. It's simply more work. And if you can't use the front end, because the front end wasn't built for it, and you can't modify it, well you're going to have to build what is effectively a new front end to solve the problem. |