Setup

# Install scala-cli (if you haven't already)
curl -sSLf https://scala-cli.virtuslab.org/get | sh

# Verify
scala-cli version
# Scala 3.x is required

Using the Example Files

Every code example in this book is available as a ready-to-run file in the examples/ directory. Clone the repository and run any example:

git clone https://github.com/hanishi/scala3-design-with-types.git
cd scala3-design-with-types

# Run a specific example
scala-cli run examples/step0/step0.scala

# Or cd into a step directory
cd examples/step2
scala-cli run step2c.scala

Each file is self-contained — just pick the step you’re reading and run the corresponding file.

Important: Always run a single file at a time — do not compile an entire directory (e.g., scala-cli compile examples/step2/). Files within a step intentionally redefine the same classes (Product, Book, Box, etc.) with different signatures to show a progression. Compiling them together will produce duplicate-definition errors.