rash - an attempt at capturing what I like about bash, as a #lang
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How to install
On Racket v6.0 and on (inside the rash directory):
raco pkg install
On versions before v6.0:
raco link .
raco setup rash # optional
How to use
To get a REPL:
racket -I rash
In a module:
#lang rash
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Motivation
As misshapen a language as it is, bash really is the right tool for
some jobs. For quick an dirty scripting, it's really hard to beat.
I don't really have a concrete explanation as to why that is, but I'll
try to pin it down as I go along. For now, here's what I have:
- your standard library is your $PATH
- interaction with the filesystem is really lightweight
- mostly implicit handling of I/O streams
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What it's currently trying to do
For now, I'm trying to see what the $PATH as the standard library
would look like in Racket. The goal is to be able to do something like
(mv "old" "new")
and have it work. For commands that are executed for side-effect,
that's straightforward. For commands that deal with std{in,out,err},
more thought is necessary to get something as nice as bash.
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What could be hacked on
It would be nice to have the Racket list comprehensions be able to
implicitly iterate on files, something like
(for ([f "subdir/*"]) ...)
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What remains to be figured out
How to handle streams (std{in,out,err}) in as lightweight a way as
bash. This includes redirection, and all.
This raises the following question: What is the functional
interpretation of bash commands? bash commands kinda take two kinds of
arguments: command-line arguments, and stdin. Similarly, they kinda
produce multiple kinds of outputs: return code, stout and stderr.
Having to manage stream piping explicitly (w.g. `with-input-from-X')
is unsatisfactory.
What's the right implicit coercion story? In bash, everthing is a
string. I guess we may want to implicitly coerce to string anything
that's passed to a bash command. What do we do in cases where
non-trivial serialization is necessary?