Plutus Limit Order Smart Contract

A complete on-chain limit order implementation for decentralized exchanges on Cardano.

Features

• ✅ Self-custodied limit orders with price+quantity guards
• ✅ Partial and full order fills
• ✅ Multiple time-in-force options (GTC, GTD, IOC, FOK)
• ✅ Fee mechanism with rebates
• ✅ Order cancellation and updates
• ✅ Price validation and execution bounds
• ✅ Expiration handling

Order Types

• GTC: Good Till Cancelled
• GTD: Good Till Date
• IOC: Immediate or Cancel
• FOK: Fill or Kill

Project Structure

src/ ├── LimitOrder/ │ ├── Types.hs -- Data types and definitions │ ├── Validator.hs -- On-chain validator logic │ ├── Helpers.hs -- Helper functions │ └── OffChain.hs -- Off-chain code └── LimitOrder.hs -- Main module export

Getting Started

Prerequisites

• Nix package manager
• Cabal
• GHC 8.10.7 or later

Development

1. Enter development environment:

   nix develop
   

Build the project: cabal build

Run tests: cabal test

Start REPL: cabal repl

Usage Example

import LimitOrder

-- Create order parameters params = OrderParams { opFeeRecipient = "fee_pkh" , opMinOrderValue = 2000000 , opMaxFeeBps = 100 }

-- Create a buy order createLimitOrder params baseAsset quoteAsset Buy 100 1 10000000 GTC Nothing True 10

Order Flow Post Order: Maker creates and funds a limit order

Fill Order: Taker fills order at or better than limit price

Cancel Order: Maker cancels unfilled portion

Update Order: Maker updates order parameters

Security Features Price validation prevents bad executions

Only order owner can cancel/update

Proper asset transfer validation

Expiration handling for GTD orders

License Apache 2.0

Complete File List Summary

src/LimitOrder/Types.hs - Data types

src/LimitOrder/Validator.hs - On-chain logic

src/LimitOrder/Helpers.hs - Helper functions

src/LimitOrder/OffChain.hs - Off-chain code

src/LimitOrder.hs - Main module

test/LimitOrderSpec.hs - Test specifications

test/Main.hs - Test runner

app/Main.hs - Example application

limit-order-contract.cabal - Cabal configuration

flake.nix - Nix flake configuration

default.nix - Nix development environment

README.md - Documentation