[alkonaut]

The problem with composable tools is that some things are really hard to compose and separate out, and have to be integrated: syntax highlighting, autocompletion and interactive debuggers are really hard to treat as separate programs.

You probably noticed how useless racer is on the command line: type code in your text editor and then when you want a completion, you go to your CLI and type "racer myfile.rs row,column" and there are your completions! :) Jokes aside: it's clearly superior (and intended) as an integrated tool than as a command line tool.

I'd argue that a debugger can offer the same kind of power being an integrated debugger as the (admittedly silly) racer example.