示例

Fibonacci two ways: naive recursion, and a tail call that becomes a loop.

FizzBuzz: match guards, string interpolation and a for over a range.

Function values: lambdas, captures, higher-order functions, effect variables.

Generics: type parameters, Option and Result, and the list builtins.

Narrow floats: bfloat16 and binary16 as values that round the way the hardware rounds.

Records: literals, field shorthand, functional update, and record patterns.

Sum types and pattern matching: a Shape ADT, guards, pipes and test blocks.

Characters and code points: making a slug, and the two renderings of a Char.

Eq and Hash: the prelude traits behind == and hashing.

Traits: a default method, impls for a record and for Int, bounded generics.

Handler state: a var declared in the arm table, and the block below the handler reading what the arms left there.

The file system as a named effect: one reader, two handlers.

Effect handlers: an interpreter that carries no environment parameter.

One-shot resumption: an answer that arrives turns later, read as the value of a let.

Effect tracking: !io in a signature, and the compiler holding you to it.

Failure in three tiers: Result with ?, catch_fault, and bracket.

Java interop, worked: the JDK's own static factories, laying out a build.

A four-function calculator: a lexer, a precedence-climbing parser, an eval.

A GPU program on a machine with no GPU: nine kernels, two sides, one handler that is a table in host memory.

A multi-module project: one directory, three modules, no manifest.

A pure-Dawn JSON validator, run against JSONTestSuite's 318 fixtures.

Qualification changes lookup, not the evidence supplied by a handler.

The whole application: a model, three messages, update and view, plus the text form of the model the wire carries between turns. No io and no host; main.dawn is the one call that connects it to one.

The pure half of the demo: model, messages, update and view. No io, no wire format, no host, so every assertion below is == on a value.

The pure half of the todo app: model, messages, update, view, and the line parser. Everything here is a value-in, value-out function, which is what the test blocks below lean on -- an interaction is asserted as data, no terminal in sight. The io shell around it is main.dawn.