Generate — CNL in, verified code out

Edit the decisions (your business and UX rules, in their own vocabularies), turn the knobs, and press Run. The engine reasons across the blocks, composes the derived features with grammapy, and emits a real Textual app — the generated source appears below, exactly what the playground drives headlessly to verify. No model is involved: every line traces to a rule.

(First run downloads the engine into your browser — a few seconds, one time. Everything then runs locally, no server.)

business.cnl — your pricing & loyalty decisions # The discount policy, as data (the numbers are KNOBS). discount_policy threshold 100 discount_policy rate 10 # A loyal (premium) customer whose order QUALIFIES earns a discount. ?cart grants_discount yes when ?cart customer_tier premium and ?cart order_qualifies yes # A granted discount is a benefit the checkout must surface. ?cart has_benefit discount when ?cart grants_discount yes

ux.cnl — what confirming & showing a discount MEAN # An IRREVERSIBLE action carries an OBLIGATION to confirm. ?cart obliged confirm when ?cart action_irreversible yes ?cart requires_feature confirmation_step when ?cart obliged confirm # "Show a discount" MEANS display it prominently — HIGHLIGHTED. ?cart requires_feature highlighted_discount when ?cart has_benefit discount

The library port — read-only (swap this to re-target a different toolkit)

textual.cnl — what the Textual toolkit can build (absorbed facts) modal_confirm supported_by textual styled_label supported_by textual input_value supported_by textual button_widget supported_by textual

bridge.cnl — the only crosswalk between the vocabularies confirmation_step realized_by modal_confirm highlighted_discount realized_by styled_label # A required UX feature is ADMITTED only if the library supports its realizer. ?feat admitted_for ?cart when ?cart requires_feature ?feat and ?feat realized_by ?cap and ?cap supported_by textual

customer premium (loyal) basic order spend irreversible (final sale) Run ▶

The library port (the Textual widget facts + the bridge crosswalk) is held fixed here — it is the part you swap to re-target a different toolkit, while these same business/UX decisions drive it. See the case for the re-target measured end-to-end.

Things to try: switch the customer to basic (the discount and its highlight drop); drop the order spend below the threshold (a premium customer stops qualifying); tick irreversible (the UX rule obliges a confirm step and the whole screen shape flips). Every change re-derives the code, with the reasoning behind it auditable.