This document describes the design goals for Kakoune, including rationale.
Unlike Vim, Kakoune does not have an underlying line-oriented editor. It is always expected to be used in an interactive fashion, displaying edited text in real time. That should not prevent Kakoune from being used non-interactively (executing a macro for example), but priority should be given to ease of interactive use.
Kakoune is a code editor. It is not an IDE, not a file browser, not a word processor and not a window manager. It should be very efficient at editing code. As a side effect, it should be very efficient at editing text in general.
Being limited in scope to code editing should not isolate Kakoune from its environment. On the contrary, Kakoune is expected to run on a Unix-like system alongside a lot of text-based tools, and should make it easy to interact with these tools.
For example, sorting lines should be done using the Unix sort command, not
with an internal implementation. Kakoune should make it easy to do that,
hence the | command for piping selected text through a filter.
The modern Unix environment is not limited to text filters. Most people use a graphical interface nowadays, and Kakoune should be able to take advantage of that without hindering text mode support. For example, Kakoune enables multiple windows by supporting many clients on the same editing session, not by reimplementing tiling and tabbing. Those responsibilities are left to the system window manager.
Kakoune features should be as orthogonal as possible. For example, in Vim, there are many ways to modify the buffer: Through normal/insert mode, command mode, and Vim scripts. In Kakoune, modifying the buffer is only the job of normal/insert mode.
That means there should be clear separation of concerns between modes:
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normal mode is for manipulating the selection and the selection contents.
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insert mode is for interactive insertion into the buffer.
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command mode is for non-editing features (opening a file, setting options…).
Orthogonality is an ideal; it should not forbid common sense pragmatism.
The gf and ga commands are not strictly selection manipulation commands,
but they do fit nicely with other goto commands, so they are acceptable in
normal mode even though they could arguably be moved to command mode.
Modes should be orthogonal, as should commands within modes. For
example, Vim uses both d and x to delete text, with minor differences. In
Kakoune only d exists, and the design ensures that x is not needed.
Kakoune should be fast — fast to use, as in a lot of editing in a few keystrokes, and fast to execute.
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Vim is the benchmark here. Most editing tasks should be doable in fewer or the same number of keystrokes as Vim.
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Kakoune is designed with asynchronicity in mind. Launching a background process and using its result when available should not block the editor.
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Kakoune should be implemented with speed in mind. A slow editor is a useless one.
Simplicity is nice. Simplicity correlates with orthogonality and speed. It makes things easier to understand, bugs easier to fix, and code easier to change.
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No threading: multithreading is a hard problem and is not well suited to a text editor:
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When we want a direct result, we need to be synchronous with the user. A 4x speed improvement is meaningless; we need to have an algorithm which appears instantaneous the user.
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When we want an asynchronous result, the processing is best left to a helper command which can be reused with other Unix tools.
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No binary plugins: shared objects by themselves add a lot of complexity. Plugins add another interface to Kakoune and go against orthogonality. The
%sh{ … }and socket interfaces should be made good enough for most plugin use cases.-
Rather than writing a plugin for intelligent code completion or source code navigation, it is better to write an independent helper tool that can interact with Kakoune through the shell.
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No integrated scripting language: for the same reason as binary plugins.
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Limited smartness: Kakoune should not try to be too smart. Being smart is often unpredictable for the user and makes things context-dependent. When Kakoune tries to be smart, it should provide the alternative, non-smart version. For instance,
*tries to detect word boundaries on the selection, butalt-*opts out of this behavior.
As an effect of both Orthogonality and Simplicity, normal mode is not a layer of keys bound to a text editing language layer. Normal mode is the text editing language.
That means there is no delete-selected-text command that d is bound
to. d is the delete selected text command.
This permits both scripting and interactive use cases to share the same text editing language. Both use normal mode to express complex editing.
Besides promoting simplicity by avoiding the introduction of another layer, this helps ensure the interactive editing language is expressive enough to handle complex use cases, such as indentation hooks.
Kakoune should not be tailored for writing in a specific programming language. Support for different languages should be provided by a kak script file. Built-in language support should be avoided.
Kakoune should be able to document its features. Live documentation, along with an extensive suggestion/completion system, provides the discoverability which is often lacking in non-GUI tools. As much as possible, documentation should be integrated with the code so that it stays up to date.