# Copyright: 2005 The Perl Foundation.  All Rights Reserved.
# $Id$

=head1 NAME

docs/req/model_users.pod - Model Users For Parrot Design Decisions

=head1 RATIONALE

This document exists to give Parrot design a direction.  Before we can
make design decisions, we need a metric to evaluate them.  The best
metrics are based on I<informed> intuition.  This document is designed
to inform the intuition.

Below are listed some model users with random (or, in some cases,
not-so-random) names.

Questions to ask yourself: Do you know anyone who fits these
descriptions?  If so, what else would you write about them?
How would you describe them?  What else do they care about?
What do they I<not> care about?

And let's remember that, in the end, we can't really please everyone.
So we have to pick who we'll please, and who we'll piss off.  It just
can't be helped.


=head1 MODEL USERS


=head2 "Autrijus": Perl 6 implementer

Autrijus has a favorite language, Perl 6, and he wants to target it
to Parrot.

Autrijus:

* values speed, but not above all else
* values interoperability of languages, especially with Perl 5
* doesn't care about PBC particularly, though he knows his users
  might, eventually
* doesn't mind incompatible source changes, as long as the entire tool
  chain still works after upgrading


=head2 "Nick": Ponie implementor

Nick is implementing Perl 5 with (over? under? inside?) Parrot.

Nick:

* doesn't care about dynamic loading of features
* ???


=head2 "Dick": Scripting an existing application

Dick has an application that needs some scripting features, so he's
embedding Parrot to get PIR and the languages that target it, e.g.
Perl 6.

Dick:

* cares mostly about ease and stability of embedding
  (no memory leaks!  no seg faults!)
* is probably not very sensitive to performance, since scripting
  interfaces are never speed demons anyway
* probably bundles a specific Parrot version (or linkage to a specific
  version) and maybe precompiled pbcs with his program
* may be more or less tolerant of changes depending on the system
  into which Parrot is embedded


=head2 "Tom": Embedded system creator

Tom loves Perl 6, so wants to write his special-purpose embedded
system to run on Parrot.  The platform is very limited, and speed
is not particularly crucial.

Tom:

* cares mostly about stable long-term execution
  (no memory leaks!  no seg faults!)
* doesn't care about inter-version compatibility,
  since he bundles Parrot with his product
* doesn't care very much about performance
* depends on PBC for space efficiency
* wants to be able to strip down Parrot for deployment,
  omitting subsystems that are large or which depend on
  large external systems


=head2 "Ilya": Intensive CPU User

Ilya writes high-performance CPU-bound code, typically involving
either intense data structure manipulation or floating point math.

Ilya:

* cares about performance to exclusion of most other factors
* doesn't care about PBC one way or the other
* can't handle incompatible source changes; is likely to pick
  a favorite feature set and stick with it


=head2 "Magpie": Lover of shiny things

Magpie sees something shiny -- a new runtime, or a new language, or
even better, a new language on a new runtime -- and is willing to do a
lot to make it work, just so he can play with it.

Magpie:

* loves neat features
* doesn't care about PBC, backwards compatibility, or any of the
  things that make a platform stable and useful for users who
  don't care about shiny tech
* will put up with almost any change as long as the inconvenience
  leads to something even more shiny

