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.

User guide and language reference

The Helios language and Helios API are covered extensively by the online book.

Online playground

There is an online coding playground.

Sponsoring

For sponsoring we prefer using the Cardano blockchain itself (instead of Patreon or Github's sponsor system).

Our Cardano address is the same one where the helioslang adahandle is located:

addr1qxyd3shxugqkrkdpwgjq522cu7h4lkr8qnz9uemd4w68p970n6h44fq8ujuyu807vll9atjpc8z6zl0pyv6n2neezysqv5rjvd

Please join our Discord and tell us what you'd like your sponsorship to be used for before sending funds.

Example

The following Helios example is equivalent to the Plutus vesting contract from the Plutus playground:

spending vesting

struct VestingTranche {
    time:  Time // 'amount' is available after '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{
    /*parameters interpolated from surrounding js*/
}

// the compiler is smart enough to add an empty Datum and empty Redeemer as arguments to the actual main entrypoint function
func main(ctx: ScriptContext) -> Bool {
    tx: Tx = ctx.tx;
    now: Time = tx.time_range.start;
    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());
// the output can be saved to a file, and that file can be used directly by cardano-cli

You can explore this example on the Helios playground.

Acknowledgements