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Deploy your rules

Publish L4 rules on Legalese Cloud, where applications and AI agents can call them.

Before you start: Install L4 and write your first rule.

You will deploy an insurance premium calculator with two published rules, one that computes a premium and one that checks whether a discount applies, and then call one of them.

Complete example:

-- insurance-premium.l4
-- Example: Exporting functions for deployment

§ `Insurance Premium Calculator`

DECLARE Applicant
    HAS `age` IS A NUMBER
        `risk score` IS A NUMBER
        `is existing customer` IS A BOOLEAN

-- The primary function, marked as the default export
@export default Calculate the insurance premium for an applicant
GIVEN applicant IS AN Applicant @desc The applicant's details
GIVETH A NUMBER
DECIDE `calculate premium` IS
    IF applicant's `risk score` > 0.7
    THEN applicant's `age` * 100
    ELSE IF applicant's `is existing customer`
         THEN applicant's `age` * 40
         ELSE applicant's `age` * 60

-- A secondary exported function
@export Check whether the applicant qualifies for a discount
GIVEN applicant IS AN Applicant @desc The applicant to check
GIVETH A BOOLEAN
DECIDE `qualifies for discount` IF
    applicant's `is existing customer`
    AND applicant's `risk score` <= 0.5

-- Internal helper — not exported (no @export annotation)
GIVEN applicant IS AN Applicant
GIVETH A NUMBER
`base rate` applicant MEANS
    IF applicant's `age` < 30 THEN 50 ELSE 80

-- Test data
`test applicant` MEANS Applicant 35 0.4 TRUE

#EVAL `calculate premium` `test applicant`
#EVAL `qualifies for discount` `test applicant`

Step 1: Mark rules with @export

@export marks a rule for publication. Put it on the line directly above the rule's GIVEN (or above the rule itself, if it has no GIVEN). The rest of the line describes the rule:

DECLARE Applicant
    HAS `age`                  IS A NUMBER
        `risk score`           IS A NUMBER
        `is existing customer` IS A BOOLEAN

@export default Calculate the insurance premium for an applicant
GIVEN applicant IS AN Applicant @desc The applicant's details
GIVETH A NUMBER
DECIDE `calculate premium` IS
    IF applicant's `risk score` > 0.7
    THEN applicant's `age` * 100
    ELSE IF applicant's `is existing customer`
         THEN applicant's `age` * 40
         ELSE applicant's `age` * 60

@export Check whether the applicant qualifies for a discount
GIVEN applicant IS AN Applicant @desc The applicant to check
GIVETH A BOOLEAN
DECIDE `qualifies for discount` IF
        applicant's `is existing customer`
    AND applicant's `risk score` <= 0.5
Annotation Meaning
@export <description> Publish this rule, with this description.
@export default <description> Publish it as the default rule, used when a caller names no rule.
@desc <description> After a GIVEN input: describe the input for people and agents calling it.

The descriptions become the rule's documentation in the API schema, and they are all an AI agent knows when it decides whether and how to call the rule, so write them with care. Rules without @export stay internal: other rules can use them, but they are not published.

An @export anywhere else, such as between GIVETH and DECIDE, is not picked up, and the rule is not published. See annotations for the details.

Step 2: Check what will be published

In VS Code, open the file, open the L4 sidebar and select the Deploy tab. It lists every exported rule in the file, with its description, inputs and result type. If the list is empty, the file has no @export or does not type-check.

Step 3: Deploy

  1. In the sidebar, sign in to your Legalese Cloud account.
  2. Check the list of exported rules.
  3. Click Deploy.
  4. Enter a deployment name, such as insurance-premium. It becomes part of the API address: 1 to 36 characters, using letters, digits, hyphens and underscores.
  5. Click Deploy Now.

The extension uploads the file and the service compiles it, and its status goes through Pending (uploaded), Compiling, then Ready (live) or Failed (with the compiler's error message).

Update a deployment

Deploying to a name that already exists updates that deployment. The extension first checks for breaking changes, such as a removed rule, a removed or renamed input, or a changed result type, and warns you before you confirm. Manage rules in git and CI explains which changes break callers.

From the command line

The l4 command deploys the same way. Sign in once with the legalese command (l4 install legalese, then legalese login), then run l4 deploy insurance-premium.l4 to create the deployment and l4 redeploy insurance-premium.l4 to update it; redeploy refuses breaking changes unless you add --force. l4 deployments lists your deployments and l4 undeploy NAME removes one. With --server, the same commands deploy to a jl4-service you run yourself. See Using the l4 CLI.

Step 4: Manage deployments

The Deployments tab in the sidebar lists your organization's deployments, with each one's rules, descriptions and inputs. From there you can open a deployment's Integrate dialog, which shows its addresses for each kind of client, or Undeploy it. Undeploying asks for confirmation, because it breaks every integration that uses the deployment.

Step 5: Call a rule

Once the deployment is Ready, each exported rule can be called over REST. Create an API key in the Legalese Cloud console, then:

curl -X POST https://api.legalese.cloud/{orgSlug}/insurance-premium/functions/calculate-premium/evaluation \
  -H "Authorization: Bearer sk_..." \
  -H "Content-Type: application/json" \
  -d '{
    "arguments": {
      "applicant": {
        "age": 35,
        "risk-score": 0.4,
        "is-existing-customer": true
      }
    }
  }'

{orgSlug} is your organization on Legalese Cloud. In the address and the arguments, spaces in names become hyphens: the rule `calculate premium` is calculate-premium, and the field `risk score` is "risk-score". The answer:

{ "contents": { "result": { "value": 1400 } }, "tag": "SimpleResponse" }

The same deployment also works with AI agents, chat clients and websites. To pick a way in, see Choose an integration; for the REST interface in detail, including the answer format, see Call rules over REST.

Common mistakes

Forgetting @export. Without it, a rule is not published, however useful it is.

Putting @export in the wrong place. It goes directly above GIVEN, not between GIVETH and the rule:

@export Square a number
GIVEN x IS A NUMBER @desc The number to square
GIVETH A NUMBER
squared x MEANS x * x

Leaving inputs undescribed. Without @desc, callers and AI agents have only the input's name to go on.

Next steps