Lesson 0.2

Setting Up

Install Go, create the project, run a test. Five minutes, then we start building.

5 min exercise

Install Go

Go 1.22 or later. Check if you already have it:

go version
# go1.22.0 or higher

If not: go.dev/dl — download, install, done. One binary, no dependencies.

Create the project

mkdir monk-lang && cd monk-lang
go mod init github.com/yourname/monk-lang

This creates go.mod — Go's dependency file. That's the entire setup. No build config, no bundler, no package manager ceremony.

Write the first test

Create syntax/scanner_test.go:

package syntax

import "testing"

func TestPlaceholder(t *testing.T) {
    // This test exists to verify your setup works.
    // It gets replaced in Phase 1.
    if 1+1 != 2 {
        t.Fatal("math is broken")
    }
}

Run it:

go test ./syntax/
# ok  github.com/yourname/monk-lang/syntax  0.001s

This is the TDD loop you'll use for the entire compiler. Write a failing test. Make it pass. Refactor. Every phase starts with a test file.

Project structure

The compiler will grow into this shape:

go.modModule definition

syntax/Phases 1-2: lexer, parser, AST, tokens

codegen/Phase 4: AST to C source

main.goPhase 5: CLI entry point (monk build/run/check)

runtime/Phase 3: C library linked into every binary

Each directory is a Go package. Tests live next to the code they test (syntax/scanner_test.go). No separate test directory.

Checkpoint

Go 1.22+ installed and on your PATH

go test ./syntax/ passes

You understand the project structure

You're ready for Phase 1. Next: the lexer.