Package: eopsin-lang
eopsinYou are building what you want. Why not also buildhowyou want?This is an implementation of smart contracts for Cardano which are written in a strict subset of valid Python.
The general philosophy of this project is to write a compiler that
ensure the following:If the program compiles then:it is a valid Python programthe output running it with python is the same as running it on-chain.Why eopsin?100% valid Python. Leverage the existing tool stack for Python, syntax highlighting, linting, debugging, unit-testing,property-based testing,verificationIntuitive. Just like Python.Flexible. Imperative, functional, the way you want it.Efficient & Secure. Static type inference ensures strict typing and optimized codeGetting StartedEopsin Pioneer ProgramCheck out theeopsin-pioneer-programfor a host of educational example contracts, test cases and off-chain code.Example repositoryCheck out theeopsin-examplerepository for a quick start in setting up a development environment
and compiling some sample contracts yourself.You can replace the contracts in your local copy of the repository with code from theexamplessection here to start exploring different contracts.Developer Community and QuestionsThis repository contains a discussions page.
Feel free to open up a new discussion with questions regarding development using eopsin and using certain features.
Others may be able to help you and will also benefit from the previously shared questions.Check out the communityhereYou can also chat with other developersin the welcoming discord
communityof OpShinInstallationInstall Python 3.8. Then runpython3.8-mpipinstalleopsin-langWriting a Smart ContractA short non-complete introduction in starting to write smart contracts follows.Make sure you understand EUTxOs, Addresses, Validators etc on Cardano.There is a wonderful crashcourse by @KtorZ. The contract will work on these conceptsMake sure you understand python. Eopsin works like python and uses python. There are tons of tutorials for python, choose what suits you best.Make sure your contract is valid python and the types check out. Write simple contracts first and run them usingeopsin evalto get a feeling for how they work.Make sure your contract is valid eopsin code. Runeopsin compileand look at the compiler erros for guidance along what works and doesn't work and why.Dig into theexamplesto understand common patterns. Check out thepreludefor understanding how the Script Context is structured and how complex datums are defined.Check out thesample repositoryto find a sample setup for developing your own contract.In summary, a smart contract in eopsin is defined by the functionvalidatorin your contract file.
The function validates that a specific value can be spent, minted, burned, withdrawn etc, depending
on where it is invoked/used as a credential.
If the function fails (i.e. raises an error of any kind such as aKeyErrororAssertionError)
the validation is denied, and the funds can not be spent, minted, burned etc.There is a subtle difference here in comparison to most other Smart Contract languages.
In eopsin a validator may return anything (in particular alsoFalse) - as long as it does not fail, the execution is considered valid.
This is more similar to how contracts in Solidity always pass, unless they run out of gas or hit an error.
So make sure toassertwhat you want to ensure to hold for validation!A simple contract called the "Gift Contract" verifies that only specific wallets can withdraw money.
They are authenticated by a signature.
If you don't understand what a pubkeyhash is and how this validates anything, check outthis gentle introduction into Cardanos EUTxO.
Also see thetutorial bypycardanofor explanations on what each of the parameters to the validator means
and how to build transactions with the contract.fromeopsin.preludeimport*@dataclass()classCancelDatum(PlutusData):pubkeyhash:bytesdefvalidator(datum:CancelDatum,redeemer:None,context:ScriptContext)->None:sig_present=Falseforsincontext.tx_info.signatories:ifdatum.pubkeyhash==s:sig_present=Trueassertsig_present,"Required signature missing"All contracts written in eopsin are 100% valid python.
Minting policies expect only a redeemer and script context as argument.
Check out theArchitecture guidefor details on how to write double functioning contracts.
Theexamplesfolder contains more examples.
Also check out theeopsin-pioneer-programandeopsin-examplerepo.CompilingWrite your program in python. You may start with the content ofexamples.
Arguments to scripts are passed in as Plutus Data objects in JSON notation.You can run any of the following commands# Evaluate script in Python - this can be used to make sure there are no obvious errorseopsinevalexamples/smart_contracts/assert_sum.py"{\"int\": 4}""{\"int\": 38}""{\"constructor\": 0, \"fields\": []}"# Compile script to 'uplc', the Cardano Smart Contract assemblyeopsincompileexamples/smart_contracts/assert_sum.pyDeployingThe deploy process generates all artifacts required for usage with common libraries likepycardano,lucidand thecardano-cli.# Automatically generate all artifacts needed for using this contracteopsinbuildexamples/smart_contracts/assert_sum.pySee thetutorial bypycardanofor explanations how to build transactions witheopsincontracts.The small printNot every valid python program is a valid smart contract.
Not all language features of python will or can be supported.
The reasons are mainly of practical nature (i.e. we can't infer types when functions likeevalare allowed).
Specifically, only a pure subset of python is allowed.
Further, only immutable objects may be generated.For your program to be accepted, make sure to only make use of language constructs supported by the compiler.
You will be notified of which constructs are not supported when trying to compile.NameEopsin (Korean: 업신; Hanja: 業神) is the goddess of the storage and wealth in Korean mythology and shamanism.
[...] Eopsin was believed to be a pitch-black snake that had ears.[1]Since this project tries to merge Python (a large serpent) and Pluto/Plutus (Greek wealth gods), the name appears fitting.The name is pronouncedop-shin.ContributingArchitectureThis program consists of a few independent components:An aggressive static type inferencerRewriting tools to simplify complex python expressionsA compiler from a subset of python into UPLCDebugging artefactsFor debugging purposes, you can also run# Compile script to 'uplc', and evaluate the script in UPLC (for debugging purposes)python3-meopsineval_uplcexamples/smart_contracts/assert_sum.py"{\"int\": 4}""{\"int\": 38}""{\"constructor\": 0, \"fields\": []}"# Compile script to 'pluto', an intermediate language (for debugging purposes)python3-meopsincompile_plutoexamples/smart_contracts/assert_sum.pySponsoringYou can sponsor the development of eopsin through GitHub orTeikior just by sending ADA. Drop me a message on social media and let me know what it is for.TeikiStake your ada to support OpShin atTeikiGitHubSponsor the developers of this project through the button "Sponsor" next to themADADonation in ADA can be submitted to$opshinoraddr1qyz3vgd5xxevjy2rvqevz9n7n7dney8n6hqggp23479fm6vwpj9clsvsf85cd4xc59zjztr5zwpummwckmzr2myjwjns74lhmr.Supporters