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til/elixir/compute-intermediate-values-in-a-with-construct.md
2019-03-14 16:23:31 -05:00

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# 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.
```elixir
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 won't leak.
See the [`with`
docs](https://hexdocs.pm/elixir/Kernel.SpecialForms.html#with/1) for more
details.