Hello World

Breyta hello world example for validating first flow push and run behavior.

Quick Answer

Use this minimal flow to verify your CLI, environment variables, and end-to-end run path before adding integrations.
Even here, keep shaping logic in top-level :functions, call it via flow/step :function, and label orchestration branches for readable run traces.

Use Case

Smallest possible flow to validate push/run wiring.

Full Definition

{:slug :hello-world
 :name "Hello World"
 :concurrency {:type :singleton :on-new-version :supersede}
 :functions [{:id :build-greeting
              :language :clojure
              :code "(fn [input] {:message (str \"Hello, \" (:name input) \"!\") :input input})"}]
 :invocations {:default
               {:inputs [{:name :name
                          :type :text
                          :label "Name"
                          :default "World"}]}}
 :interfaces {:manual [{:id :run :label "Run" :invocation :default :enabled true}]}
 :flow
 '(let [input (flow/input)
        greeting-input ^{:label "Greeting target"
                         :yes "Use provided name"
                         :no "Fallback to World"}
                       (if (:name input)
                         input
                         (assoc input :name "World"))
        output (flow/step :function :build-output
                 {:ref :build-greeting
                  :input greeting-input})]
    {:breyta.viewer/kind :markdown
     :breyta.viewer/options {:title "Greeting"}
     :breyta.viewer/value (str "# Greeting\n\n" (:message output))})}

Run It

breyta flows push --file ./tmp/flows/hello-world.clj
breyta flows validate hello-world
breyta flows run hello-world --wait

Optional input:

breyta flows run hello-world --wait --input '{"name":"Ada"}'

Expected Output

A Markdown output artifact with a short greeting. The intermediate function
still returns structured data, but the final :flow return value is shaped as a
human-readable viewer artifact.

See Output Artifacts for the full final
output viewer contract.

Why This Matters

This example validates the full authoring and runtime path with minimal noise.

no external bindings required
deterministic result shape
safe baseline for CLI/environment troubleshooting

If this fails, fix environment or CLI workflow before building larger flows.

Customize in this order:

input shape
output contract
:requires and external steps