Why Bach?

Bach is a general-purpose programming language designed in particular for writing “one-liners” for text processing on the command line. It is designed to have the following properties:

• Concise. One-liners are quick to type, there is not much boiler plate.
• Readable. Bach programs consist mostly of English words. Bach makes minimal use of special characters. You can read a Bach program and get an idea of what it does even without being familiar with the language.
• Flowing. Bach programs are evaluated from left to right, and can be read and understood thus.
• Orthogonal. Bach’s language elements are designed so that there is one – and preferably only one – obvious way to do any given task. This makes life easier for both writers and readers of Bach programs. When in doubt, orthogonality trumps conciseness.

A Bach program is a series of functions. They are just written next to each other with spaces in between. Each function’s output is the next function’s input. In technical terms, a Bach program is a composition of its component functions. Schematically, this Bach program

f g h

corresponds to this expression in a traditional applicative programming language,

h(g(f))

and to this Unix pipeline:

f | g | h

In Bach, the concept of function composition is so central that there is no operator for it (like | in Unix shells or . in Haskell). It’s just what you get when you put two or more functions next to each other.