Scsh – Scheme as a Unix shell

I'd love to see something a bit less trivial, like iterating over the output of another command to run some other commands

    for i in `bin/hosts`; do ssh $i uptime; done

This is certainly an interesting use of Scheme macros for a shell-like DSL. For a long time I've mused over ideas for a Unix-ish shell that embeds first-class access to a richer scripting language than typical shell scripting. In this light, Scsh is similar to many other projects I've seen over the years in various languages, in that its effective aim is more about shell-like scripting in an alternate language.

For my goals where all of these attempts fall down, including Scsh, is in the syntax. One of the best aspects of working in the various Unix shells is their very low syntactic ceremony. I find that even similar "shell nouveau" attempts in Ruby are cumbersome, despite that language having relatively low syntactic ceremony for a full programming language. E.g. I don't want to have to write even one function/method call just to run a program. That's far too heavyweight for a user shell, even when the least it adds are a pair of parens.

For a new shell that I'd actually want to use, there seem to be two key criteria:

1. There needs to be a radically low-ceremony user interface that respects everything we've learned from Unix shells over the years. Perhaps it's best to think of this UI as its own DSL inspired by a subset of existing shell UI. This includes staples such as pipeline composability, etc. Ironically, the best new-generation examples of this principle seem to be GUI launcher tools like Quicksilver and its conceptual offspring. While far from being Unix shells, they can be seen as a wonderful generalization/simplification of the essential shell " " + completion UI.

2. A seamless way to enter "write real code" mode, where the focus of "real code" is on shell power-user workflows and customizing and extending shell functionality. I'm not interested in making this into yet another standalone scripting tool, since there are a plethora of choices for modern languages that cover this ground. E.g. if one uses a shell backed by a mature language such as Scheme/Ruby/Python/etc. then the normal runtimes for those languages can support standalone scripting use. As needed, useful idioms developed in the shell environment could easily be exported as a library for use in standalone scripts. (And again, I think Scsh's shell-like macros are a great example of that.)

ShellJS [1] for Javascript

[1] https://github.com/arturadib/shelljs

I think Emacs eshell hits the sweet spot with this. Behaves like a normal shell for common tasks, with the ability to drop down to S-exprs if need be.