Helios Lang
Helios is a Domain Specific Language that compiles to Plutus-Core (i.e. Cardano on-chain validator scripts). Helios is a non-Haskell alternative to Plutus.
Helios is purely functional, strongly typed, and has a simple curly braces syntax. It notably supports closures, compile-time evaluation, and enums as tagged unions.
The Helios library contains a reference compiler for the Helios language, as well as transaction building functions. Everything is written in Javascript.
Use the following tutorial to learn how to use Helios with cardano-cli:
- Cardano-node setup
- Wallet setup and funding
- Always Succeeds contract
- Time Lock contract
- Subscription contract
- Minting policy scripts
- English Auction contract
We are in the process of migrating these tutorials here.
There is an online coding playground.
Acknowledgements
Quick start examples
1. Vesting contract example
The following Helios example is equivalent to the Plutus vesting contract from the Plutus playground:
spending vesting
struct VestingTranche {
time: Time
amount: Value
func available_from(self, time: Time) -> Value {
if (time >= self.time) {
self.amount
} else {
Value::ZERO
}
}
func remaining_from(self, time: Time) -> Value {
self.amount - self.available_from(time)
}
}
struct VestingParams {
tranche1: VestingTranche
tranche2: VestingTranche
owner: PubKeyHash
func remaining_from(self, time: Time) -> Value {
self.tranche1.remaining_from(time) + self.tranche2.remaining_from(time)
}
}
const PARAMS: VestingParams = VestingParams{
}
func main(ctx: ScriptContext) -> Bool {
tx: Tx = ctx.tx;
now: Time = tx.now();
remaining_actual: Value = tx.value_locked_by(ctx.get_current_validator_hash());
remaining_expected: Value = PARAMS.remaining_from(now);
remaining_actual >= remaining_expected && tx.is_signed_by(PARAMS.owner)
}
You can compile this source into Plutus-Core using the helios.js
library:
import * as helios from "helios.js"
const src = `struct VestingTranche {
...
...
`;
console.log(helios.Program.new(src).compile().serialize());
You can explore this example on the Helios playground.
2. Deserialize Plutus-Core
import * as helios from "helios.js"
const plutusCoreJson = `{"type": "PlutusScriptV1", ...}`;
console.log(helios.deserializePlutusCore(plutusCoreJson));
Helios user guide and language reference
Can be found here.