#Patterns and limits

##Guarded requests

# @when vars.has("auth.token")
GET {{base_url}}/bearer
Authorization: {{= "Bearer " + vars.get("auth.token") }}

##Controlled branching in workflows

# @switch last.statusCode
# @case 401 run=Refresh
# @case 200 run=Upsert
# @default fail="unexpected status"

##Reusable module logic

module users
export fn label(user) {
  return (user.name ?? "unknown") + " <" + (user.email ?? "n/a") + ">"
}

# @use ./rts/users.rts
X-User: {{= users.label(user) }}

##Limits and safety

RestermScript enforces hard limits to prevent runaway scripts and keep the UI responsive. These limits include maximum steps per evaluation, maximum call depth, maximum string size, maximum list size, maximum dict size, and an optional timeout. When a limit is exceeded, evaluation fails with a detailed error.

##Design constraints and why they exist

RestermScript prioritizes predictable evaluation and safe execution. It does not allow file writes or network access, and file reads are limited to json.file when enabled. It does not allow member assignment because it reduces side effects and simplifies the interpreter. It requires an explicit alias or module name to avoid name collisions and keep imports explicit. It keeps host objects read-only in most contexts because request evaluation should remain declarative. It sorts dict keys during range to keep iteration order deterministic across runs.

If you need full scripting or side effects, use JavaScript @script blocks. For everything else, RestermScript is the safer and more readable choice.