Today I Learned

A Hashrocket project

Compute Intermediate Values In A With Construct

The expressions you use in a with construct do not have to contain the <- syntax. You can pattern match and bind values along the way as well.

with %{id: id} <- get_user(),
     url = "/api/#{id}/blogs",
     %{status_code: 200, body: body} <- HTTPoison.get(url),
     {:ok, decoded_body} <- Poison.decode(body) do
  {:ok, decoded_body}
end

In the above (sorta contrived) example we were able to construct a URL in the middle of the series of expressions.

The values we compute inline will be closed into the with construct, so they wonโ€™t leak.

See the with docs for more details.

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