A good operating system with a decent text editor built in
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Hunter
It's one of the most extensible pieces of software available out there. For non-popular languages like Lisp, Haskell, or Erlang, it is usually the editor of choice because its language syntax and navigation support are superb. Key combinations are not intuitive the first time you use this program. Most people using this program on a daily basis remap certain keys (Caps lock as Control, for example).
Pros: First class support for Lisp and other functional languages. If you know Lisp, you can change anything in the editor. Free and open source software.
Cons: Key combinations are not easy for the fingers (you can change them). It's not preinstalled in every Unix box. Memory usage is higher than other editors. Startup time can be worse than other editors (especially if you've customized Emacs heavily).
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