[erlang-questions] List comprehensions assistance

[Technion]

Hi,

Just a slight update, it took a bit more wrangling to get the correct format (ie, something jiffy liked)

    ScanConverted = [{[{<<"address">>, list_to_binary(inet:ntoa(X))},
                  {<<"stat">>, Y}]} || {X, Y} <- Results],


________________________________________
From: erlang-questions-bounces@REDACTED <erlang-questions-bounces@REDACTED> on behalf of Technion <technion@REDACTED>
Sent: Tuesday, 18 August 2015 12:17 PM
To: Hugo Mills
Cc: Erlang Questions
Subject: Re: [erlang-questions] List comprehensions assistance

Hi Hugo,

Many thanks for the response.

Argh! Nothing worse than spending hours on something only to introduce a dumb mistake on the home stretch.
________________________________________
From: Hugo Mills <hugo@REDACTED>
Sent: Tuesday, 18 August 2015 8:44 AM
To: Technion
Cc: Erlang Questions
Subject: Re: [erlang-questions] List comprehensions assistance

On Mon, Aug 17, 2015 at 10:40:35PM +0000, Technion wrote:
> Hi,
>
>
> I have the following piece of code, which works correctly:
>
>
>    ConvertFun = fun({X, Y}) -> {[{<<"address">>,
>             list_to_binary(inet:ntoa(X))}, {<<"stat">>, Y}]} end,
>     ScanConverted = lists:map(ConvertFun, Results),
>
>
> The reason for this very specific mapping is to convert it into exactly the format jiffy expects (in order to generate the correct JSON). I've been experimenting with rewriting this as a list comprehension (largely as a learning exercise).
>
>
> Code like this fails to compile:
>
>
>     ScanConverted = [[{<<"address">>, list_to_binary(inet:ntoa(X))},
>                   {<<"stat">>, Y}]| {X, Y} <- Results]
>
>
> src/ipmangle.erl:31: syntax error before: '<-'
>
>
> Any pointers on this would be appreciated.

   A list comprehension is [ Expr || Var <- List ]. You have
[ Expr | Var <- List ].

   Hugo.

PS. Yay! One I can answer! ;)

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