defaultManagerSettings not in scope in Network.HTTP.Conduit

Question

In http-conduit version 2.0+ I want to create a custom Manager.

The documentation states that defaultManagerSettings should be used in newManager.

import Network.HTTP.Conduit
main = do manager <- newManager defaultManagerSettings
          print $ content

However, when trying to run it I get the following error:

conduittest.hs:3:33:
    Not in scope: `defaultManagerSettings'
    Perhaps you meant `conduitManagerSettings' (imported from Network.HTTP.Conduit)

Shall I use conduitManagerSettings instead? If not, where can I import defaultManagerSettings from?

Note: This question intentionally does not show further research effort, because it was immediately answered in a Q&A-style manner.

Answer 1

As listed in the newManager docs, you can import defaultManagerSettings like this:

import Network.HTTP.Client (defaultManagerSettings)

Let's have a look what conduitManagerSettings is:

conduitManagerSettings :: ManagerSettings
conduitManagerSettings = tlsManagerSettings

In Network.HTTP.Client.TLS, tlsManagerSettings is defined as follows:

tlsManagerSettings :: ManagerSettings
tlsManagerSettings = mkManagerSettings def Nothing

Ok, so nothing special here. def is from the Data.Default module and therefore defines the default instance. However defaultManagerSettings specifies all default values.

I wasn't able to track down where the instance Default ManagerSettings resides. However I think it is safe to assume that mkManagerSettings def Nothing has the same settings as defaultManagerSettings.

I personally recommend to use defaultManagerSettings, because any of these behaviours might change in the future.