diff --git a/init.sql b/init.sql
index bfc7df8..796eed8 100644
--- a/init.sql
+++ b/init.sql
@@ -20,18 +20,18 @@ CREATE TABLE markets(
active BOOLEAN DEFAULT true
);
CREATE EXTENSION "uuid-ossp";
-CREATE TABLE contracts(
+CREATE TABLE shares(
id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
market_id INTEGER REFERENCES markets(id),
description TEXT NOT NULL,
- quantity DOUBLE PRECISION NOT NULL
+ quantity BIGINT NOT NULL DEFAULT 0
);
CREATE TYPE order_side AS ENUM ('BUY', 'SELL');
CREATE TABLE trades(
id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
- contract_id UUID NOT NULL REFERENCES contracts(id),
+ share_id UUID NOT NULL REFERENCES shares(id),
pubkey TEXT NOT NULL REFERENCES users(pubkey),
side ORDER_SIDE NOT NULL,
- quantity DOUBLE PRECISION NOT NULL,
+ quantity BIGINT NOT NULL,
msats BIGINT NOT NULL
);
diff --git a/src/market.go b/src/market.go
index 960ed19..076ba7d 100644
--- a/src/market.go
+++ b/src/market.go
@@ -1,32 +1,20 @@
package main
import (
- "errors"
"math"
)
-// logarithmic market scoring rule (LMSR) market maker from Robin Hanson:
-// https://mason.gmu.edu/~rhanson/mktscore.pdf
-func BinaryLMSRBuy(invariant int, funding int, tokensAQ float64, tokensBQ float64, sats int) (float64, error) {
- k := float64(invariant)
- f := float64(funding)
- numOutcomes := 2.0
- expA := -tokensAQ / f
- expB := -tokensBQ / f
- if k != math.Pow(numOutcomes, expA)+math.Pow(numOutcomes, expB) {
- // invariant should not already be broken
- return -1, errors.New("invariant already broken")
- }
- // AMM converts order into equal amount of tokens per outcome and then solves equation to fix invariant
- // see https://docs.gnosis.io/conditionaltokens/docs/introduction3/#an-example-with-lmsr
- newTokensA := tokensAQ + float64(sats)
- newTokensB := tokensBQ + float64(sats)
- expB = -newTokensB / f
- x := newTokensA + f*math.Log(k-math.Pow(numOutcomes, expB))/math.Log(numOutcomes)
- expA = -(newTokensA - x) / f
- if k != math.Pow(numOutcomes, expA)+math.Pow(numOutcomes, expB) {
- // invariant should not be broken
- return -1, errors.New("invariant broken")
- }
- return x, nil
+func costFunction(b float64, q1 float64, q2 float64) float64 {
+ // reference: http://blog.oddhead.com/2006/10/30/implementing-hansons-market-maker/
+ return b * math.Log(math.Pow(math.E, q1/b)+math.Pow(math.E, q2/b))
+}
+
+// logarithmic market scoring rule (LMSR) market maker from Robin Hanson:
+// https://mason.gmu.edu/~rhanson/mktscore.pdf1
+func BinaryLMSR(invariant int, funding int, q1 int, q2 int, dq1 int) float64 {
+ b := float64(funding)
+ fq1 := float64(q1)
+ fq2 := float64(q2)
+ fdq1 := float64(dq1)
+ return costFunction(b, fq1+fdq1, fq2) - costFunction(b, fq1, fq2)
}
diff --git a/src/router.go b/src/router.go
index 12ae9ec..f9d007b 100644
--- a/src/router.go
+++ b/src/router.go
@@ -26,18 +26,17 @@ type Market struct {
Active bool
}
-type Contract struct {
+type Share struct {
Id string
MarketId int
Description string
- Quantity float64
+ Quantity int
}
type MarketDataRequest struct {
- ContractId string `json:"contract_id"`
- OrderSide string `json:"side"`
- Sats int `json:"sats,omitempty"`
- Quantity float64 `json:"quantity,omitempty"`
+ ShareId string `json:"share_id"`
+ OrderSide string `json:"side"`
+ Quantity int `json:"quantity"`
}
func (t *Template) Render(w io.Writer, name string, data interface{}, c echo.Context) error {
@@ -205,27 +204,27 @@ func market(c echo.Context) error {
} else if err != nil {
return err
}
- rows, err := db.Query("SELECT id, market_id, description, quantity FROM contracts WHERE market_id = $1 ORDER BY description DESC", marketId)
+ rows, err := db.Query("SELECT id, market_id, description, quantity FROM shares WHERE market_id = $1 ORDER BY description DESC", marketId)
if err != nil {
return err
}
defer rows.Close()
- var contracts []Contract
+ var shares []Share
for rows.Next() {
- var contract Contract
- rows.Scan(&contract.Id, &contract.MarketId, &contract.Description, &contract.Quantity)
- contracts = append(contracts, contract)
+ var share Share
+ rows.Scan(&share.Id, &share.MarketId, &share.Description, &share.Quantity)
+ shares = append(shares, share)
}
data := map[string]any{
"session": c.Get("session"),
"Id": market.Id,
"Description": market.Description,
- "Contracts": contracts,
+ "Shares": shares,
}
return c.Render(http.StatusOK, "binary_market.html", data)
}
-func marketData(c echo.Context) error {
+func marketCost(c echo.Context) error {
var req MarketDataRequest
err := c.Bind(&req)
if err != nil {
@@ -241,38 +240,31 @@ func marketData(c echo.Context) error {
c.Logger().Error(err)
return c.JSON(http.StatusInternalServerError, map[string]string{"status": "ERROR", "reason": "internal server error"})
}
- rows, err := db.Query("SELECT id, market_id, description, quantity FROM contracts WHERE market_id = $1", marketId)
+ rows, err := db.Query("SELECT id, market_id, description, quantity FROM shares WHERE market_id = $1", marketId)
if err != nil {
return err
}
defer rows.Close()
- var contracts []Contract
+ var shares []Share
for rows.Next() {
- var contract Contract
- rows.Scan(&contract.Id, &contract.MarketId, &contract.Description, &contract.Quantity)
- contracts = append(contracts, contract)
+ var share Share
+ rows.Scan(&share.Id, &share.MarketId, &share.Description, &share.Quantity)
+ shares = append(shares, share)
}
- sats := req.Sats
- quantity := req.Quantity
- // contract A is always the contract which is bought or sold
- contractAIdx := slices.IndexFunc(contracts, func(c Contract) bool { return c.Id == req.ContractId })
- contractBIdx := 0
- if contractAIdx == 0 {
- contractBIdx = 1
+ dq1 := req.Quantity
+ // share 1 is always the share which is bought or sold
+ share1idx := slices.IndexFunc(shares, func(s Share) bool { return s.Id == req.ShareId })
+ share2idx := 0
+ if share1idx == 0 {
+ share2idx = 1
}
- contractAQ := contracts[contractAIdx].Quantity
- contractBQ := contracts[contractBIdx].Quantity
- if req.OrderSide == "BUY" && sats > 0 {
- quantity, err := BinaryLMSRBuy(1, market.Funding, contractAQ, contractBQ, sats)
- if err != nil {
- return err
- }
- return c.JSON(http.StatusOK, map[string]string{"status": "OK", "quantity": fmt.Sprint(quantity)})
+ q1 := shares[share1idx].Quantity
+ q2 := shares[share2idx].Quantity
+ if req.OrderSide == "SELL" {
+ dq1 = -dq1
}
- if req.OrderSide == "SELL" && quantity > 0 {
- // TODO implement BinaryLMSRSell
- }
- return c.JSON(http.StatusBadRequest, map[string]string{"status": "ERROR", "reason": "bad request"})
+ cost := BinaryLMSR(1, market.Funding, q1, q2, dq1)
+ return c.JSON(http.StatusOK, map[string]string{"status": "OK", "cost": fmt.Sprint(cost)})
}
func serve500(c echo.Context) {
diff --git a/src/server.go b/src/server.go
index 0198d53..5c77a6c 100644
--- a/src/server.go
+++ b/src/server.go
@@ -61,7 +61,7 @@ func main() {
e.GET("/api/session", checkSession)
e.POST("/logout", logout)
e.GET("/market/:id", sessionGuard(market))
- e.POST("/api/market/:id/data", sessionGuard(marketData))
+ e.POST("/api/market/:id/cost", sessionGuard(marketCost))
e.Use(middleware.LoggerWithConfig(middleware.LoggerConfig{
Format: "${time_custom} ${method} ${uri} ${status}\n",
CustomTimeFormat: "2006-01-02 15:04:05.00000-0700",
diff --git a/template/binary_market.html b/template/binary_market.html
index 4205f0e..b2da54a 100644
--- a/template/binary_market.html
+++ b/template/binary_market.html
@@ -36,33 +36,37 @@
{{.Description}}
- {{ range .Contracts }} {{ if eq .Description "YES" }}
+ {{ range .Shares }} {{ if eq .Description "YES" }}
{{ else }}
{{ end }}
{{ end }}
- {{ range .Contracts }} {{ if eq .Description "YES" }}
+ {{ range .Shares }} {{ if eq .Description "YES" }}
{{ else }}
{{ end }}
@@ -76,7 +80,8 @@
const yesSellBtn = document.querySelector("#yes-sell")
const yesSideInput = document.querySelector("#yes-side")
const yesQuantityInput = document.querySelector("#yes-quantity")
- const yesSatsInput = document.querySelector("#yes-sats")
+ const yesCostDisplay = document.querySelector("#yes-cost")
+ const yesCostLabel = document.querySelector("#yes-cost-label")
const yesSubmitLabel = document.querySelector("#yes-submit-label")
const noOrderBtn = document.querySelector("#no-order")
@@ -85,7 +90,8 @@
const noSellBtn = document.querySelector("#no-sell")
const noSideInput = document.querySelector("#no-side")
const noQuantityInput = document.querySelector("#no-quantity")
- const noSatsInput = document.querySelector("#no-sats")
+ const noCostDisplay = document.querySelector("#no-cost")
+ const noCostLabel = document.querySelector("#no-cost-label")
const noSubmitLabel = document.querySelector("#no-submit-label")
yesOrderBtn.onclick = function () {
@@ -98,22 +104,28 @@
yesSideInput.value = "BUY"
yesBuyBtn.classList.add("selected")
yesSellBtn.classList.remove("selected")
- yesSubmitLabel.textContent = 'BUY YES contracts'
+ yesCostLabel.textContent = 'cost [sats]'
+ yesSubmitLabel.textContent = 'BUY YES shares'
+ yesQuantityInput.value = undefined
+ yesCostDisplay.value = undefined
}
yesSellBtn.onclick = function () {
yesSideInput.value = "SELL"
yesBuyBtn.classList.remove("selected")
yesSellBtn.classList.add("selected")
- yesSubmitLabel.textContent = 'SELL NO contracts'
+ yesCostLabel.textContent = 'payout [sats]'
+ yesSubmitLabel.textContent = 'SELL NO shares'
+ yesQuantityInput.value = undefined
+ yesCostDisplay.value = undefined
}
- yesSatsInput.onchange = async function(e) {
- const sats = parseInt(e.target.value, 10)
+ yesQuantityInput.onchange = async function(e) {
+ const quantity = parseInt(e.target.value, 10)
const body = {
- contract_id: "{{(index .Contracts 0).Id}}",
- sats,
+ share_id: "{{(index .Shares 0).Id}}",
+ quantity,
side: yesSideInput.value
}
- const rBody = await fetch("/api/market/{{.Id}}/data", {
+ const rBody = await fetch("/api/market/{{.Id}}/cost", {
method: "POST",
headers: {
"Content-type": "application/json"
@@ -126,8 +138,7 @@
return null
})
if (!rBody) return null;
- const quantity = rBody.quantity
- yesQuantityInput.value = quantity
+ yesCostDisplay.value = parseFloat(Math.abs(rBody.cost)).toFixed(3)
}
noOrderBtn.onclick = function () {
noOrderBtn.classList.add("selected")
@@ -139,22 +150,28 @@
noSideInput.value = "BUY"
noBuyBtn.classList.add("selected")
noSellBtn.classList.remove("selected")
- noSubmitLabel.textContent = 'BUY NO contracts'
+ noCostLabel.textContent = 'cost [sats]'
+ noSubmitLabel.textContent = 'BUY NO shares'
+ noQuantityInput.value = undefined
+ noCostDisplay.value = undefined
}
noSellBtn.onclick = function () {
noSideInput.value = "SELL"
noBuyBtn.classList.remove("selected")
noSellBtn.classList.add("selected")
- noSubmitLabel.textContent = 'SELL YES contracts'
+ noCostLabel.textContent = 'payout [sats]'
+ noSubmitLabel.textContent = 'SELL YES shares'
+ noQuantityInput.value = undefined
+ noCostDisplay.value = undefined
}
- noSatsInput.onchange = async function(e) {
- const sats = parseInt(e.target.value, 10)
+ noQuantityInput.onchange = async function(e) {
+ const quantity = parseInt(e.target.value, 10)
const body = {
- contract_id: "{{(index .Contracts 1).Id}}",
- sats,
+ share_id: "{{(index .Shares 1).Id}}",
+ quantity,
side: noSideInput.value
}
- const rBody = await fetch("/api/market/{{.Id}}/data", {
+ const rBody = await fetch("/api/market/{{.Id}}/cost", {
method: "POST",
headers: {
"Content-type": "application/json"
@@ -167,8 +184,7 @@
return null
})
if (!rBody) return null;
- const quantity = rBody.quantity
- noQuantityInput.value = quantity
+ noCostDisplay.value = parseFloat(Math.abs(rBody.cost)).toFixed(3)
}