The power of capitalism Haskell in your terminal!
dosh is a Haskell Read-Eval-Print Loop, or REPL for short.
While other REPLs for Haskell exist, this one aims to be good enough to replace Bash as a daily driver.
We offer:
- syntax highlighting
- advanced history interaction
- LSP-powered autocompletion and error detection
Why not? Haskell is an advanced functional programming language with an excellent blend of power and elegance that scales well as commands grow nontrivial.
This is the Unix philosophy: Write programs that do one thing and do it well. Write programs to work together. Write programs to handle text streams, because that is a universal interface.
— Doug McIlroy
Aside from executing programs, an essential operation of the shell is to manipulate text streams that pass between programs. Many programs output structured data, which Bash is notoriously bad at handling.
There are many alternatives to Bash, but they are all fundamentally boring shells. They tend to invent new domain specific languages which ultimately offer no real value as a programming language.
Instead of inventing a new shell language that can do slighty more than Bash, why not go the other way around and make an existing language usable as a shell? And what language is more suitable than one that was quite literally invented as a testbed for novel uses such as this?
Because our REPL has special handling of Haskell's do notation.
In Haskell, the keyword do introduces a block of commands that evaluate sequentially and can depend on each other.
When the user enters a do block in dosh, the prompt changes to do$, which is also where the logo comes from.
I've also been advised to avoid overt references to Haskell in the name (e.g. hashell, shellmonad), as those might spook people.
This is not a novel idea, as evidenced by the abundance of Haskell libaries that provide shell primitives. The only novelty of this project is a snazzy REPL around them.
- turtle: Shell programming, Haskell-style
- shh: Simple shell scripting from Haskell
- shelly: shell-like (systems) programming in Haskell
- ptGHCi is a high-powered REPL for Haskell, inspired by IPython
- Using Haskell as my shell (2021) by Las Safin
- Use Haskell for shell scripting (2015) by Gabriella Gonzalez