How can I stream the output of Enum.to_list to text for insertion into an editor?

|> Enum.reduce("", fn(struct, string) -> string <> "iso: #{struct.iso}, name: #{struct.name}\n" end)

will give you

iso: nz, name: New Zealand
iso: gb, name: United Kingdom

I have got that part working. What I need is to save the output to a file. Currently it is just being output in iex.

|> (&File.write(path_to_file, &1)).()

If you want to stream the whole thing you should be able to do

File.stream!("tmp.csv") \
|> DataMorph.structs_from_csv("open-register", :iso_country) \
|> Stream.map(fn(struct) -> "iso: #{struct.iso}, name: #{struct.name}\n" end) \
|> Stream.into(File.stream!("output.txt")) \
|> Stream.run

When I append the &File.write as you suggested this is the error I get

File.stream!('template_params_import.csv') \
|> DataMorph.structs_from_csv("voip-provisioning", :tpl_params) \
|> Enum.to_list \
|> &File.write('template_params_import.key.list', &1)
v
warning: piping into a unary operator is deprecated. You could use e.g. Kernel.+(5) instead of +5
  iex:7

** (ArgumentError) cannot pipe Enum.to_list(DataMorph.structs_from_csv(File.stream!('template_params_import.csv'), "voip-provisioning", :tpl_params)) into &(File.write('template_params_import.key.list', &1)), can only pipe into local calls foo(), remote calls Foo.bar() or anonymous functions calls foo.()
    (elixir) lib/macro.ex:149: Macro.pipe/3
    (stdlib) lists.erl:1263: :lists.foldl/3
    (elixir) expanding macro: Kernel.|>/2
             iex:7: (file)

This is the exact example from the DataMorph page. I need the exact output shown (which is commented) to go into the output file, ie the output printed in iex.

File.stream!('./tmp.csv') \
|> DataMorph.structs_from_csv("open-register", :iso_country) \
|> Enum.to_list
# [
#   %OpenRegister.IsoCountry{iso: "nz", name: "New Zealand"},
#   %OpenRegister.IsoCountry{iso: "gb", name: "United Kingdom"}
# ]

First reduce to a string as per my first comment, then write to the file. Alternatively, just stream the whole thing.

If you really want the exact output—brackets, percent signs, and all—then you can do

...
|> Enum.to_list \
|> inspect(limit: :infinity) \ 
|> (&(&1 <> "\n")).() \
|> (&File.write("output.txt", &1)).()

Does this code came after the Enum.to_list or after DataMorph.structs_from_csv?

inspect(limit: :infinity) comes after Enum.list. If you don’t need the Elixir syntax to be a part of the output though, I would highly recommend using one of the options.

File.stream!("tmp.csv") \
|> DataMorph.structs_from_csv("open-register", :iso_country) \
|> Stream.map(fn(struct) -> "iso: #{struct.iso}, name: #{struct.name}\n" end) \
|> Stream.into(File.stream!("output.txt")) \
|> Stream.run