Types

Scalar types are string, int, bool, path, file, directory, bytes, status, stream, void, any, unknown, and never. Collections initially include string[], int[], bool[], map<string, string>, and map<string, int>. A suffix ? makes a value optional.

Arithmetic requires numeric-compatible input. A literal 42 is int; quoted text is string; command substitution is string unless declarations say otherwise. In strict mode, unsafe external values are unknown until narrowed. For example, passing 42 to string host reports WIZ4001 Argument 1 of serve expects string, but received int.

declare -T int attempts=1
attempts="many"

src/main.wiz:2:1 WIZ4001 Cannot assign string to int attempts

With strict: true, an untyped assignment is unknown; it can be interpolated as text but cannot be used in arithmetic or passed into a typed parameter until checked. With strict mode disabled it becomes any. implicitAny: false rejects that inference, and allowAny: false rejects an explicit -T any.

bytes is intentionally not assignable to string. It represents opaque, file-backed binary data so NUL bytes never enter a shell variable. Use the bytes operations described in Binary data to capture, pipe, save, or emit the payload.