Two sequential HTTP requests

Question

Sorry for newbie's question (and for my english) :)

I tries to write the following function:

• the function downloads a content from URL1 (it's received as argument)
• the function parses this content and extract URL2
• the function downloads a content from URL2
• the content from URL2 is a result of this function
• if an error was occured, this function should return Nothing

I know how to execute the HTTP requests. I have a function to parse the request from URL1. But I don't know how:

• to execute new request with extracted URL2
• to ignore second request if URL2 isn't extracted (or error in URL1 is occured)

Answer 1

I principle you want something like this:

import Maybe
import Http

type Url = String
getContentFromUrl : Maybe Url -> Maybe String
getContentFromUrl url = --your implementation
extractUrlFromContent : Maybe String -> Maybe Url
extractUrlFromContent content = --your implementation
content = getContentFromUrl (Just "http://example.com") 
          |> extractUrlFromContent 
          |> getContentFromUrl