Values and Literals

Pkl starts with ordinary values. Before object modeling or module composition, make sure scalar syntax is boring in a good way: comments document intent, numbers stay readable, strings can derive labels, and units keep operational values explicit.

Comments

Pkl has line comments, block comments, and doc comments. Use doc comments for members that should be visible to generated documentation.

/// Public port exposed by the service.port: Int = 8080// Internal toggle for this deployment.debug = false

Numbers and Booleans

Integers support decimal, hexadecimal, binary, and octal notation. Underscores can group digits without changing the value. Floats use decimal notation, and booleans use true and false.

retries = 3mask = 0xffenabled = trueratio = 0.95budget = 1_000_000

Strings

Strings support escapes, interpolation, multiline literals, and custom delimiters. Prefer interpolation when a label depends on another value.

service = "api"label = "\(service)-production"message = """service: \(service)mode: production"""

Null

null is explicit. Add ? to a type when absence is meaningful, then use ??, ?., or !! intentionally.

description: String? = nullsummary = description ?? "No description"summaryLength = description?.length ?? 0

Durations and Data Sizes

Use units instead of encoding operational quantities as plain strings.

timeout = 30.scacheTtl = 5.minmemory = 512.mbdisk = 20.gb

Reading Order

Read this page before Types and Constraints. Values are the surface syntax; types and constraints explain how those values are accepted, rejected, or refined.