implement funds

[chadwhitacre]

The idea here it to provide a way to lump individuals together into groups and projects for funding purposes. A "fund" here is a set of weighted percentages for individuals and other funds (funds can be nested). Then we use these funds as levels of indirection when shuffling money around each week on payday.

Was: group tips together for simultaneous adjustment

I believe this is what @joelmccracken is asking for on #434. The coarse-grained case would be adjusting all tips at once (#448). This ticket is for grouping tips together so that you could adjust 10 tips at once without touching the other 20. The language that Joel used was "a single tip covering multiple people."

[chadwhitacre]

After conversations with @MikeFair in email and IRC, I'm now looking at this as the answer to the question of aggregating individuals into groups on Gittip.

!m @joelmccracken

[chadwhitacre]

Gittip users can create one or more "funds" (as I'm calling them). A fund is a mapping of participant_id to integer weight:

{ foo: 1000
, bar: 400
, baz: 200
, buz: 10
 }

The part of the Gittip profile page where you see everyone you're giving to ... that becomes a UI over this data structure. Then in the API (#462) we have this as an endpoint that can be posted to by the Gittip UI as well as by third-party applications. Then, we allow for funds to be the keys as well:

{ foo: 1000
, "bar/baz": 400
, baz: 200
, buz: 10
 }

One thing to tease out is the interplay between absolute dollar amounts and percentages. Another is how to keep the damper on volatility.

Next step for me here is some paper prototypes ...

[chadwhitacre]

Just got off the horn with @MikeFair. He had the interesting idea of implementing this using CouchDB. We would store funds as full json docs in there, and use Couch's map-reduce implementation to compute dollar amounts from there. He's offered to spike that out for us. Reticketing as #488.

[chadwhitacre]

Users have zero, one, or more funds. We create a "default" fund for them when they register (cf. #489). In the UI we want there to be a default fund, to streamline the simple case where a user has a single fund. (Whether we enforce a one-fund minimum under the hood or allow the user to drop to zero funds is an implementation detail.)

All funds are public. When I go to a profile page I see a list of funds that the user has created, as well as the weekly dollar amount being given to each fund. These are also shown on community pages (#496). Funds are anonymous in that the allocation of each fund is not public. Users can't be part of their own funds. Non-self users and other funds can be part of funds.

Users allocate dollar amounts to funds. They no longer allocate dollar amounts directly to other Gittip accounts.

Each payday, the fund graph is reduced to dollar amounts from one account to another.

Issues subsumed by this one: #27, #55, #94, #216, #316, #327, #372, #434, #448.