Scalus Language Guide

Learn how to write smart contracts for Cardano using Scala 3. This guide covers Scalus language features, syntax, and programming patterns for building efficient, type-safe validators that compile to Plutus Core.

Introduction

• Why Scala 3? - Discover why Scala 3 is ideal for blockchain development. Learn about its multi-platform versatility, industry-proven reliability, and how it’s used by major financial institutions and tech companies.
• Supported Scala Features - Understand which Scala features are supported when compiling to Plutus Core, including lambdas, pattern matching, higher-order functions, and more.

Fundamental Types

• Primitive Types - Work with Plutus primitive types using familiar Scala syntax: Unit, Boolean, BigInt, ByteString, String, and Data.
• Custom Data Types - Define smart contract data structures using case classes and enums that automatically serialize to Plutus Data.
• Collections - Use immutable List, AssocMap (key-value pairs), and efficient collection operations for on-chain data manipulation.

Programming Constructs

• Functions - Write named functions, lambdas, recursive functions, and higher-order functions. Learn about function composition and currying for functional programming patterns.
• Control Flow - Control program execution with if-then-else, pattern matching on case classes and enums, and handling conditional logic efficiently.
• Builtin Functions - Access Plutus builtin functions for cryptographic operations, byte string manipulation, list operations, and blockchain-specific utilities.

Advanced Topics

• Modules - Organize code into reusable modules with @Compile, create shareable libraries, and build modular smart contract architectures.

Language Constraints

Scalus compiles to Untyped Plutus Core (UPLC), a minimalist lambda calculus optimized for blockchain execution. This means only a subset of Scala features is supported - those that can be efficiently translated to UPLC while maintaining security and determinism.

Supported: Functions, pattern matching, case classes, enums, higher-order functions, recursion, given/using, inline macros

Not Supported: Try-catch (except throw), mutable variables (var), complex pattern matching, JVM-specific features, effects, arbitrary type class instances

See Supported Scala Features for the complete list.

Getting Started

New to Scalus? Start with:

1. Why Scala 3? - Understand the language choice
2. Primitive Types - Learn the basic building blocks
3. Your First Smart Contract - Write your first validator

Already familiar with Scala? Jump to Supported Features to understand the constraints, then explore Builtin Functions for blockchain-specific operations.