Keyboard shortcuts

Press ← or → to navigate between chapters

Press S or / to search in the book

Press ? to show this help

Press Esc to hide this help

The API Client

Fetch wrappers for the shortn server. Uses Result for error handling.

(bind api-base "http://localhost:8080")

(export (async (func shorten-url
  :args (:string url)
  :body
  (try
    (bind response (await (fetch (template api-base "/api/shorten") (obj
      :method "POST"
      :headers (new Headers #a(#a("Content-Type" "application/json")))
      :body (JSON:stringify (obj :url url))))))
    (if (not response:ok)
      (Err "server error")
      (Ok (await (response:json))))
    (catch e
      (Err (template "network error: " e:message)))))))

(export (async (func list-entries
  :body
  (try
    (bind response (await (fetch (template api-base "/api/list"))))
    (if (not response:ok)
      (Err "failed to load entries")
      (Ok (await (response:json))))
    (catch e
      (Err (template "network error: " e:message)))))))

Each function returns Result — either Ok with data or Err with a message. The caller uses match:

(async (func refresh-entries
  :body
  (match (await (list-entries))
    ((Ok entries) (set-entries entries))
    ((Err message) (set-error message)))))

Chapter 10’s pattern, applied to real HTTP requests.