Skip to content

Commit 300c524

Browse files
dckcdckc
committed
feat(fast-usdc): deposit, withdraw liquidity in exchange for shares
1 parent fc0d103 commit 300c524

7 files changed

+329
-131
lines changed

‎packages/fast-usdc/src/exos/liquidity-pool.js

+107
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,107 @@
1+
/**
2+
* @import {Zone} from '@agoric/zone';
3+
* @import {USDCProposalShapes} from '../pool-share-math.js'
4+
*/
5+
6+
import { AmountMath } from '@agoric/ertp/src/amountMath.js';
7+
import { M } from '@endo/patterns';
8+
import { SeatShape } from '@agoric/zoe/src/typeGuards.js';
9+
import {
10+
deposit as depositCalc,
11+
makeParity,
12+
withdraw as withdrawCalc,
13+
} from '../pool-share-math.js';
14+
import { makeProposalShapes } from '../type-guards.js';
15+
16+
/**
17+
* @param {Zone} zone
18+
* @param {ZCF} zcf
19+
* @param {Record<'USDC', Brand<'nat'>>} brands
20+
*/
21+
export const prepareLiquidityPoolKit = (zone, zcf, brands) => {
22+
return zone.exoClassKit(
23+
'Fast Liquidity Pool',
24+
{
25+
depositHandler: M.interface('depositHandler', {
26+
handle: M.call(SeatShape, M.any()).returns(undefined),
27+
}),
28+
withdrawHandler: M.interface('withdrawHandler', {
29+
handle: M.call(SeatShape, M.any()).returns(undefined),
30+
}),
31+
public: M.interface('public', {
32+
makeDepositInvitation: M.call().returns(M.promise()),
33+
makeWithdrawInvitation: M.call().returns(M.promise()),
34+
}),
35+
},
36+
/**
37+
* @param {ZCFMint<'nat'>} shareMint
38+
*/
39+
shareMint => {
40+
const { brand: PoolShares } = shareMint.getIssuerRecord();
41+
const { USDC } = brands;
42+
const proposalShapes = makeProposalShapes({ USDC, PoolShares });
43+
const dust = AmountMath.make(USDC, 1n);
44+
const shareWorth = makeParity(dust, PoolShares);
45+
const { zcfSeat: poolSeat } = zcf.makeEmptySeatKit();
46+
return { shareMint, shareWorth, poolSeat, PoolShares, proposalShapes };
47+
},
48+
{
49+
depositHandler: {
50+
/** @param {ZCFSeat} lp */
51+
handle(lp) {
52+
const { shareWorth, shareMint, poolSeat } = this.state;
53+
/** @type {USDCProposalShapes['deposit']} */
54+
// @ts-expect-error ensured by proposalShape
55+
const proposal = lp.getProposal();
56+
const post = depositCalc(shareWorth, proposal);
57+
// COMMIT POINT
58+
const mint = shareMint.mintGains(post.payouts);
59+
zcf.atomicRearrange(
60+
harden([
61+
[lp, poolSeat, proposal.give],
62+
[mint, lp, post.payouts],
63+
]),
64+
);
65+
this.state.shareWorth = post.shareWorth;
66+
lp.exit();
67+
mint.exit();
68+
},
69+
},
70+
withdrawHandler: {
71+
/** @param {ZCFSeat} lp */
72+
handle(lp) {
73+
const { shareWorth, shareMint, poolSeat } = this.state;
74+
/** @type {USDCProposalShapes['withdraw']} */
75+
// @ts-expect-error ensured by proposalShape
76+
const proposal = lp.getProposal();
77+
const { zcfSeat: burn } = zcf.makeEmptySeatKit();
78+
const post = withdrawCalc(shareWorth, proposal);
79+
// COMMIT POINT
80+
zcf.atomicRearrange(
81+
harden([
82+
[lp, burn, proposal.give],
83+
[poolSeat, lp, post.payouts],
84+
]),
85+
);
86+
shareMint.burnLosses(proposal.give, burn);
87+
this.state.shareWorth = post.shareWorth;
88+
lp.exit();
89+
burn.exit();
90+
},
91+
},
92+
public: {
93+
makeDepositInvitation() {
94+
const { depositHandler: handler } = this.facets;
95+
const { deposit: shape } = this.state.proposalShapes;
96+
return zcf.makeInvitation(handler, 'Deposit', undefined, shape);
97+
},
98+
makeWithdrawInvitation() {
99+
const { withdrawHandler: handler } = this.facets;
100+
const { withdraw: shape } = this.state.proposalShapes;
101+
return zcf.makeInvitation(handler, 'Withdraw', undefined, shape);
102+
},
103+
},
104+
},
105+
);
106+
};
107+
harden(prepareLiquidityPoolKit);

‎packages/fast-usdc/src/fast-usdc.contract.js

+21-2
Original file line numberDiff line numberDiff line change
@@ -2,10 +2,13 @@ import { BrandShape } from '@agoric/ertp/src/typeGuards.js';
22
import { withOrchestration } from '@agoric/orchestration';
33
import { M } from '@endo/patterns';
44
import { assertAllDefined } from '@agoric/internal';
5+
import { AssetKind } from '@agoric/ertp';
6+
import { provideSingleton } from '@agoric/zoe/src/contractSupport/durability.js';
57
import { prepareTransactionFeed } from './exos/transaction-feed.js';
68
import { prepareSettler } from './exos/settler.js';
79
import { prepareAdvancer } from './exos/advancer.js';
810
import { prepareStatusManager } from './exos/status-manager.js';
11+
import { prepareLiquidityPoolKit } from './exos/liquidity-pool.js';
912

1013
/**
1114
* @import {OrchestrationPowers, OrchestrationTools} from '@agoric/orchestration/src/utils/start-helper.js';
@@ -39,17 +42,33 @@ export const contract = async (zcf, privateArgs, zone, tools) => {
3942
assert(tools, 'no tools');
4043
const terms = zcf.getTerms();
4144
assert('USDC' in terms.brands, 'no USDC brand');
42-
assert('PoolShares' in terms.brands, 'no PoolShares brand');
4345

4446
const statusManager = prepareStatusManager(zone);
4547
const feed = prepareTransactionFeed(zone);
4648
const settler = prepareSettler(zone, { statusManager });
4749
const advancer = prepareAdvancer(zone, { feed, statusManager });
50+
const makeLiquidityPoolKit = prepareLiquidityPoolKit(zone, zcf, {
51+
USDC: terms.brands.USDC,
52+
});
4853
assertAllDefined({ feed, settler, advancer, statusManager });
4954

5055
const creatorFacet = zone.exo('Fast USDC Creator', undefined, {});
5156

52-
return harden({ creatorFacet });
57+
// NOTE: all kinds are defined above, before possible remote call.
58+
const shareMint = await provideSingleton(
59+
zone.mapStore('mint'),
60+
'PoolShare',
61+
() =>
62+
zcf.makeZCFMint('PoolShares', AssetKind.NAT, {
63+
decimalPlaces: 6,
64+
}),
65+
);
66+
const publicFacet = zone.makeOnce(
67+
'Fast USDC Public',
68+
() => makeLiquidityPoolKit(shareMint).public,
69+
);
70+
71+
return harden({ creatorFacet, publicFacet });
5372
};
5473
harden(contract);
5574

‎packages/fast-usdc/src/pool-share-math.js

+37-56
Original file line numberDiff line numberDiff line change
@@ -29,6 +29,19 @@ export const makeParity = (numerator, denominatorBrand) => {
2929
return makeRatio(value, numerator.brand, value, denominatorBrand);
3030
};
3131

32+
/**
33+
* @typedef {{
34+
* deposit: {
35+
* give: { USDC: Amount<'nat'> },
36+
* want?: { PoolShare: Amount<'nat'> }
37+
* },
38+
* withdraw: {
39+
* give: { PoolShare: Amount<'nat'> }
40+
* want: { USDC: Amount<'nat'> },
41+
* }
42+
* }} USDCProposalShapes
43+
*/
44+
3245
/**
3346
* Compute Shares payout from a deposit proposal, as well as updated shareWorth.
3447
*
@@ -51,77 +64,53 @@ export const makeParity = (numerator, denominatorBrand) => {
5164
* Shares = ToPool / shareWorth
5265
*
5366
* @param {ShareWorth} shareWorth previous to the deposit
54-
* @param {Amount<'nat'>} ToPool as in give.ToPool
55-
* @param {Amount<'nat'>} [wantShares] as in want.Shares
56-
* @returns {{ Shares: Amount<'nat'>; shareWorth: ShareWorth }}
67+
* @param {USDCProposalShapes['deposit']} proposal
68+
* @returns {{ payouts: { PoolShare: Amount<'nat'> }; shareWorth: ShareWorth }}
5769
*/
58-
export const deposit = (shareWorth, ToPool, wantShares) => {
59-
assert(!isEmpty(ToPool)); // nice diagnostic provided by proposalShape
70+
export const deposit = (shareWorth, { give, want }) => {
71+
assert(!isEmpty(give.USDC)); // nice diagnostic provided by proposalShape
6072

6173
const { denominator: sharesOutstanding, numerator: poolBalance } = shareWorth;
6274

63-
const Shares = divideBy(ToPool, shareWorth); // TODO: floorDivideBy???
64-
if (wantShares) {
65-
isGTE(Shares, wantShares) ||
66-
Fail`deposit cannot pay out ${q(wantShares)}; ${q(ToPool)} only gets ${q(Shares)}`;
75+
const PoolShare = divideBy(give.USDC, shareWorth); // TODO: floorDivideBy???
76+
if (want?.PoolShare) {
77+
isGTE(PoolShare, want.PoolShare) ||
78+
Fail`deposit cannot pay out ${q(want.PoolShare)}; ${q(give.USDC)} only gets ${q(PoolShare)}`;
6779
}
68-
const outstandingPost = add(sharesOutstanding, Shares);
69-
const balancePost = add(poolBalance, ToPool);
80+
const outstandingPost = add(sharesOutstanding, PoolShare);
81+
const balancePost = add(poolBalance, give.USDC);
7082
const worthPost = makeRatioFromAmounts(balancePost, outstandingPost);
71-
return harden({ Shares, shareWorth: worthPost });
83+
return harden({ payouts: { PoolShare }, shareWorth: worthPost });
7284
};
7385

74-
/**
75-
* @param {Record<'pool' | 'lp' | 'mint', ZCFSeat>} seats
76-
* @param {Record<'Shares' | 'ToPool', Amount<'nat'>>} amounts
77-
* @returns {TransferPart[]}
78-
*/
79-
export const depositTransfers = (seats, { ToPool, Shares }) =>
80-
harden([
81-
[seats.lp, seats.pool, { ToPool }, { Pool: ToPool }],
82-
[seats.mint, seats.lp, { Shares }],
83-
]);
86+
const isGT = (x, y) => isGTE(x, y) && !isEqual(x, y);
8487

8588
/**
8689
* Compute payout from a withdraw proposal, along with updated shareWorth
8790
*
8891
* @param {ShareWorth} shareWorth
89-
* @param {Amount<'nat'>} Shares from give
90-
* @param {Amount<'nat'>} FromPool from want
91-
* @returns {{ shareWorth: ShareWorth, FromPool: Amount<'nat'> }}
92+
* @param {USDCProposalShapes['withdraw']} proposal
93+
* @returns {{ shareWorth: ShareWorth, payouts: { USDC: Amount<'nat'> }}}
9294
*/
93-
export const withdraw = (shareWorth, Shares, FromPool) => {
94-
assert(!isEmpty(Shares));
95-
assert(!isEmpty(FromPool));
95+
export const withdraw = (shareWorth, { give, want }) => {
96+
assert(!isEmpty(give.PoolShare));
97+
assert(!isEmpty(want.USDC));
9698

97-
const payout = multiplyBy(Shares, shareWorth);
98-
isGTE(payout, FromPool) ||
99-
Fail`cannot withdraw ${q(FromPool)}; ${q(Shares)} only worth ${q(payout)}`;
99+
const payout = multiplyBy(give.PoolShare, shareWorth);
100+
isGTE(payout, want.USDC) ||
101+
Fail`cannot withdraw ${q(want.USDC)}; ${q(give.PoolShare)} only worth ${q(payout)}`;
100102
const { denominator: sharesOutstanding, numerator: poolBalance } = shareWorth;
101-
isGTE(poolBalance, FromPool) ||
102-
Fail`cannot withdraw ${q(FromPool)}; only ${q(poolBalance)} in pool`;
103-
!isEqual(FromPool, poolBalance) ||
104-
Fail`cannot withdraw ${q(FromPool)}; pool cannot be empty`;
103+
isGT(poolBalance, want.USDC) ||
104+
Fail`cannot withdraw ${q(want.USDC)}; only ${q(poolBalance)} in pool`;
105105
const balancePost = subtract(poolBalance, payout);
106106
// giving more shares than are outstanding is impossible,
107107
// so it's not worth a custom diagnostic. subtract will fail
108-
const outstandingPost = subtract(sharesOutstanding, Shares);
108+
const outstandingPost = subtract(sharesOutstanding, give.PoolShare);
109109

110110
const worthPost = makeRatioFromAmounts(balancePost, outstandingPost);
111-
return harden({ shareWorth: worthPost, FromPool: payout });
111+
return harden({ shareWorth: worthPost, payouts: { USDC: payout } });
112112
};
113113

114-
/**
115-
* @param {Record<'pool' | 'lp' | 'burn', ZCFSeat>} seats
116-
* @param {Record<'Shares' | 'FromPool', Amount<'nat'>>} amounts
117-
* @returns {TransferPart[]}
118-
*/
119-
export const withdrawTransfers = (seats, { Shares, FromPool }) =>
120-
harden([
121-
[seats.pool, seats.lp, { Pool: FromPool }, { FromPool }],
122-
[seats.lp, seats.burn, { Shares }],
123-
]);
124-
125114
/**
126115
* @param {ShareWorth} shareWorth
127116
* @param {Amount<'nat'>} fees
@@ -130,11 +119,3 @@ export const withFees = (shareWorth, fees) => {
130119
const balancePost = add(shareWorth.numerator, fees);
131120
return makeRatioFromAmounts(balancePost, shareWorth.denominator);
132121
};
133-
134-
/**
135-
* @param {Record<'fees' | 'pool', ZCFSeat>} seats
136-
* @param {Record<'Fees', Amount<'nat'>>} amounts
137-
* @returns {TransferPart[]}
138-
*/
139-
export const feeTransfers = (seats, { Fees }) =>
140-
harden([[seats.fees, seats.pool, { Fees }]]);

‎packages/fast-usdc/src/type-guards.js

+17-10
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,10 @@
11
import { M } from '@endo/patterns';
22

3+
/**
4+
* @import {TypedPattern} from '@agoric/internal'
5+
* @import {USDCProposalShapes} from './pool-share-math'
6+
*/
7+
38
/**
49
* @param {Brand} brand must be a 'nat' brand, not checked
510
* @param {NatValue} [min]
@@ -8,14 +13,16 @@ export const makeNatAmountShape = (brand, min) =>
813
harden({ brand, value: min ? M.gte(min) : M.nat() });
914

1015
/** @param {Record<'PoolShares' | 'USDC', Brand<'nat'>>} brands */
11-
export const makeProposalShapes = ({ PoolShares, USDC }) =>
12-
harden({
13-
deposit: M.splitRecord(
14-
{ give: { ToPool: makeNatAmountShape(USDC, 1n) } },
15-
{ want: { Shares: makeNatAmountShape(PoolShares) } },
16-
),
17-
withdraw: M.splitRecord({
18-
give: { Shares: makeNatAmountShape(PoolShares, 1n) },
19-
want: { FromPool: makeNatAmountShape(USDC, 1n) },
20-
}),
16+
export const makeProposalShapes = ({ PoolShares, USDC }) => {
17+
/** @type {TypedPattern<USDCProposalShapes['deposit']>} */
18+
const deposit = M.splitRecord(
19+
{ give: { USDC: makeNatAmountShape(USDC, 1n) } },
20+
{ want: { PoolShare: makeNatAmountShape(PoolShares) } },
21+
);
22+
/** @type {TypedPattern<USDCProposalShapes['withdraw']>} */
23+
const withdraw = M.splitRecord({
24+
give: { PoolShare: makeNatAmountShape(PoolShares, 1n) },
25+
want: { USDC: makeNatAmountShape(USDC, 1n) },
2126
});
27+
return harden({ deposit, withdraw });
28+
};

0 commit comments

Comments
 (0)