Re: [Caml-list] [ANN] OCamp - Reactive programming in the shell

["Frédéric Bour" <frederic.bour@lakaban.net>]

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I am trying to specialize in /elaborate jokes/ :).

The idea and implementation started as a joke… But with some hindsight, 
this might not be completely inappropriate.
In any case the current implementation is really just a proof of 
concept, not to be trusted at all.

On 02/04/2015 14:19, Anthony Tavener wrote:
> Hah! You were serious? I thought with commands like hipp and stir, and 
> your legal review notice at the end, that this was an April Fool's 
> joke. :)
>
> On Thu, Apr 2, 2015 at 12:38 PM, Frédéric Bour 
> <frederic.bour@lakaban.net <mailto:frederic.bour@lakaban.net>> wrote:
>
>     Code is finally available at:
>     https://github.com/def-lkb/ocamp
>
>     Sorry for the little delay!
>
>
>     On 01/04/2015 22:32, Frédéric Bour wrote:
>
>         OCamp extends unix shells with constructions to express
>         memoization, sharing of computations and reactive programming.
>
>         # Subcommands
>
>         ## fire
>
>         Just wrap a unix command with "ocamp fire" to enable the
>         extension:
>           $ ocamp fire bash
>
>         This will spawn a new bash session where the following
>         subcommands are enabled.
>
>         ## hipp
>
>           $ ocamp hipp <command>
>
>         Will memoize the output and exit status of <command>.
>         Later calls to the same <command> won't lead to actual
>         execution, but just to a duplication of its previous output.
>         Concurrent calls to <command> will just share the same
>         process, the beginning of the output being replayed to later
>         callers.
>
>         The identity of a command is defined by its arguments and
>         working directory.
>
>         ## stir
>
>           $ ocamp stir <command>
>
>         Indicate potential changes in the output if <command> was rerun.
>         Later calls to `hipp` will recompute <command> as if it was
>         not yet memoized.
>
>         ## (un)follow
>
>           $ ocamp follow <command>
>
>         First, <command> is memoized if it was not the case yet.
>         Then changes to dependencies of <command> will trigger a
>         reevaluation.
>         Use `stir` to notify a change.
>
>         (to follow is an hipp/stir reactivity).
>
>         ## pull
>
>           $ ocamp pull <command>
>
>         Closely related to `hipp`, but instead of marking dependency
>         on the output of <command>, the dependency applies to the
>         "effects" of <command>.
>
>         Thus, if `stir` is used:
>         - all pullers will be reevaluated.
>         - hippers will be reevaluated only if the output is different.
>
>         ## Summary
>
>           $ ocamp fire <command> - setup a new session alive until
>         <command> exits
>                   pull <command> - mark dependency on effects of <command>
>                   hipp <command> - mark dependency on output of <command>
>                   stir <command> - notify that <command> might have
>         been updated
>                   follow <command> - eval <command>, and reactively
>         recompute it
>                                      whenever one of its dependencies
>         change.
>                   unfollow <command> - stop recomputing <command> when
>         dependencies
>                                        change
>
>         hipp and pull provide memoization.
>         stir and follow bring a flavor of reactive programming.
>
>         # Examples
>
>         ## Fibonacci
>
>           $ cat fib.sh
>           #!/bin/sh
>           ARG="$1"
>           if [ "$ARG" -le 1 ]; then
>             echo "$ARG"
>           else
>             A=`ocamp hipp ./fib.sh $((ARG-1))`
>             B=`ocamp hipp ./fib.sh $((ARG-2))`
>             echo $((A+B))
>           fi
>
>           $ time ocamp fire ./fib.sh 50
>           12586269025
>             real    0m0.391s
>           user    0m0.153s
>           sys     0m0.060s
>
>         ## Build-system
>
>         `ocamp` provides simple primitives to construct and manage a
>         dependency graph.
>
>         This might be a saner foundation to base a build-system on
>         than make(1):
>         - the command focus on one specific problem
>         - no dsl is involved; rules can be plain unix commands,
>         including a shell, rather than a make-flavored simulation of shell
>         - nothing is provided for resolving goals; indeed this is
>         better left to tools specifically built for goal-search.
>
>         A quick'n'dirty script building ocamp itself is provided as an
>         example.
>
>         # Future
>
>         The current release is a proof-of-concept and should be
>         considered alpha quality.
>         The two features planned next are a way to make the graph
>         persistent (all data is kept in memory atm) and an interface
>         to debug and/or observe graph construction.
>
>         Note: code is undergoing legal review and should be available
>         soon \o/
>
>
>
>     -- 
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>
>


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