Re: [9fans] typed sh (was: what features would you like in a shell?)

[Bakul Shah <bakul+plan9@bitblocks.com>]

On Thu, 02 Apr 2009 20:28:57 BST roger peppe <rogpeppe@gmail.com>  wrote:
> 2009/4/2  <fgergo@gmail.com>:
> i wanted to go a little beyond sh while stopping
> short of the type profligacy of most other languages,
> hoping to create a situation where many commands
> used exactly the same types, and hence were
> viable to pipeline together.

Nitpick: the output type of one command and the input type of
the next command in the pipeline has to match, not every
command.

> a pipeline is an amazingly powerful thing considering
> that it's not a turing-complete abstraction.

"f | g" is basically function composition, where f and g are
stream functions. Of course, this simple analogy breaks down
the moment we add more input/output channels -- may be that
is why anything beyond a simple pipeline seems to get people
in trouble (see the rc output redirection thread).

To go beyond simple char streams, one can for example build a
s-expr pipeline: a stream of self identifying objects of a
few types (chars, numbers, symbols, lists, vectors). In Q
(from kx.com) over an IPC connection you can send strings,
vectors, dictionaries, tables, or arbitray Q expressions. But
there the model is more of a client/server.