encryfoundation / prismlang

Contract-oriented expression-based scripting language

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PrismLang

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PrismLang is a Contract Oriented statically typed programming language developed for the EncryCore blockchain protocol.

Language Specification

Supported Data Types

Primitive Data Types

  • Any - a supertype of any other type
  • Unit - a type with a single value ()
  • Byte - 8 bit signed integer
  • Int - 64 bit signed integer
  • Bool - a type with two logical values true and false
  • String - arbitrary sequence of chars

Collections

  • Array[T] - arrays of arbitrary length with all values of type T
  • Tuple - tuple of possibly different data types supported in PrismLang

Built-in Complex Types

  • Signature25519 - is Edwards-curve Digital Signature Algorithm (EdDSA) over Curve25519
  • Transaction - EncryTransaction
  • State - Information about current height of the blockchain, timestamp of the last published block
  • Box - EncryBox
  • AssetBox - EncryAssetBox
  • DataBox - EncryDataBox

Build-in functions

  • Str2Time(time: String) - Convert String to Timestamp
  • checkSig(signature: Signature25519, message: Array[Byte], key: Array[Byte]) - Check message was signed with Key

Build-in cryptographic hash functions

  • Blake2b256Hash(input: Array[Byte]): Array[Byte]
  • Blake2b512Hash(input: Array[Byte]): Array[Byte]
  • Keccak256Hash(input: Array[Byte]): Array[Byte]
  • Keccak512Hash(input: Array[Byte]): Array[Byte]
  • Sha256Hash(input: Array[Byte]): Array[Byte]

Basic Syntax

// Constant definition
let a: Int = 10                       // Explicit type annotation
let b = 100                           // Type will be inferred automatically
let c = if (a > b) true else false    // Conditional assignment

// Function definition
def sum(a: Int, b: Int): Int = {
    a + b
}

// Lambda definition
lamb (a: Int, b: Int) = a + b

// If statement
let flag: Bool = if (10 < 100) {
    true
} else {
    false
}

// Type matching
let validProof: Bool = if (let sig: Signature25519 = poof) checkSig(sig, msg, pk) else false

// Base58 string
let pubKeyBytes: Array[Byte] = base58'75Gs7HHUNnoEzsPgRRVABzQaC3UZVcayw9NY457Kx5p'

// Byte
let byte: Byte = (127).toByte

// Collections
let ageList: Array[Int] = List(1, 2, 3, 4)
let ageDict: Dict[String, Int] = Dict('Alice' -> 4, 'Bob' -> 9, 'Tom' -> 17) [Scheduled for the next release]

// Collection subscription
let someonesAge = ageList[0]            // Will result in `1`

// Lambda application
let doesExist: Bool = ageList.exists(lamb (i: Int) = i > 3)             // true
let ageListDoubled: Array[Int] = ageList.map(lamb (i: Int) = i * 2)     // Array(2, 4, 6, 8)

Contract Example

contract (signature: Signature25519) {
    let ownerPubKey = base58"GtBn7qJwK1v1EbB6CZdgmkcvt849VKVfWoJBMEWsvTew"
    checkSig(ctx.transaction.msg, ownerPubKey, signature)
}

Even more Contract Examples

About PrismLang

PrismLang has the following design:

  • Compiled
  • Strong typed
  • Static type-checking

PrismLang was developed in such way for a reason. For example in Ethereum, which is one of the biggest blockchain platforms nowadays, miners use gas as execution fee for every operation made on Ethereum to get paid exactly for the computational resources they spend on this operation. This sometimes leads to OutOfGasError: when the user didn't attach enough gas to execute his transaction, gas is paid to the miner, because he was spending computational power, but the transaction will not be sent to the blockchain.

PrismLang Structure is able to overcome this issue by statically analyzing the source code structure we can precisely estimate the computational cost of the operations. PrismLang does not support looping or recursion primitives for the end user, that leads to the fact, then in the compile time, we already know exactly how many operations we need to perform. Taking the previous statement into consideration, we can conclude that PrismLang can provide both end user and miner with precise Cost of the smart contract.

Furthermore, EncryCore protocol uses an Unspent Transaction Output(UTXO) model for the record keeping and smart contracts are used to lock the transaction output. Therefore, the main features kept in mind for PrismLang development were :

  1. The simplicity of usage.
  2. Clearness of the abstractions.
  3. Acceptable entry threshold.
  4. Ability to precisely estimate Cost of the operations in a convenient way for both end user and miner.

License

All contributions are made under the GNU General Public License v3. See LICENSE.