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

[roger peppe <rogpeppe@gmail.com>]

2009/4/2  <fgergo@gmail.com>:
> On Thu, Apr 2, 2009 at 8:41 PM, John Stalker <stalker@maths.tcd.ie> wrote:
>> What I most often miss in shell programming is a proper type system.
> You should have a look at alphabet. It is cool.
> http://www.vitanuova.com/inferno/man/1/sh-alphabet.html

i certainly enjoyed creating it. unfortunately it's
unfinished - i ran into unwarranted-complexity problems
trying to simulate polymorphism with processes and channels...
limbo's not a great language for writing interpreters in
when you don't know all your types in advance.

for those thinking of ideas for new shells,
i still think there's mileage in some of alphebet's ideas,
principally the way it lives in a half-way house between almost
no types (sh) and unrestricted types (most other languages).
that idea came from the thought that part of what makes
sh so powerful is the fact that so many commands
use the same types (string, stream of bytes + exit status).

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.

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

alphabet was actually a generalisation of the fs command
(see http://www.vitanuova.com/inferno/man/1/fs.html),
that i'd found really useful (and more powerful than other
filesystem traversal tools i've seen, for minimal code).

some time i'll finish it!