[erlang-questions] prettypr and spec

[Roberto Ostinelli]

I have this code:

%%%%%%%%%%%%%%%%%%%%%%%%

-module(mymodule).

-export([hello/0, goodbye/0, greetings/1]).

-spec hello() -> string().

hello() ->

greetings("hello").

-spec goodbye() -> string().

goodbye() ->

greetings("goodbye").

-spec greetings(Text::string()) -> string().

greetings(Text) ->

lists:flatten(io_lib:format("~s sublimerl", [Text])).

-ifdef(TEST).

-include_lib("eunit/include/eunit.hrl").

simple_test() ->

?assertEqual("hey sublimerl", greetings("hey")).

greetings_test_() ->

[?_assertEqual("hey sublimerl", greetings("hey"))].

-endif.

%%%%%%%%%%%%%%%%%%%%%%%%

when i convert it using this:

%%%%%%%%%%%%%%%%%%%%%%%%

Formatted = case epp_dodger:parse_file(FilePath) of

{ok, Forms} ->

case lists:keymember(error, 1, Forms) of

false ->

erl_prettypr:format(erl_recomment:recomment_forms(Forms, erl_comment_scan:file(FilePath)));

true ->

""

end;

{error, _} ->

""

end

%%%%%%%%%%%%%%%%%%%%%%%%

I get:

%%%%%%%%%%%%%%%%%%%%%%%%

-module(mymodule).

-export([hello/0, goodbye/0, greetings/1]).

-spec({{hello, 0},

       [{type, 4, 'fun',

[{type, 4, product, []}, {type, 4, string, []}]}]}).

hello() -> greetings("hello").

-spec({{goodbye, 0},

       [{type, 8, 'fun',

[{type, 8, product, []}, {type, 8, string, []}]}]}).

goodbye() -> greetings("goodbye").

-spec({{greetings, 1},

       [{type, 12, 'fun',

[{type, 12, product,

  [{ann_type, 12,

    [{var, 12, 'Text'}, {type, 12, string, []}]}]},

 {type, 12, string, []}]}]}).

greetings(Text) ->

    lists:flatten(io_lib:format("~s sublimerl", [Text])).

-ifdef(TEST).

-include_lib("eunit/include/eunit.hrl").

simple_test() ->

    ?assertEqual("hey sublimerl", (greetings("hey"))).

greetings_test_() ->

    [?_assertEqual("hey sublimerl", (greetings("hey")))].

-endif.

%%%%%%%%%%%%%%%%%%%%%%%%

What happens to spec? What is the best way to use an erlang auto-formatter?

Any input welcome.

r.

[Anthony Ramine]

Though it doesn't support erl_syntax trees, erl_pp does support pretty-printing of specs and types.

Regards,

--
Anthony Ramine

Le 25 sept. 2012 à 06:00, Roberto Ostinelli a écrit :

> What happens to spec? What is the best way to use an erlang auto-formatter?
>
> Any input welcome.

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[Ulf Wiger]

Roberto,

It appears as if erl_pp:form/1 does a much better job of formatting specs,

but then, of course, you lose the comments.

There is also an issue with typed record fields, which seems to affect 

erl_prettypr as well. It simply removes the types from record declarations.

Take a look at parse_trans_pp:beam/1. It makes no effort to preserve comments

(naturally, since it doesn't expect to find any), but handles specs and typed 

records correctly.

https://github.com/uwiger/parse_trans/blob/master/src/parse_trans_pp.erl#L71

This module, BTW, is also made to be used as an escript, and I have the 

following convenient alias:

alias pp='escript /Users/uwiger/git/parse_trans/ebin/parse_trans_pp.beam'

Not that the last point was particularly relevant to your particular problem. :)

BR,

Ulf W

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Ulf Wiger, Co-founder & Developer Advocate, Feuerlabs Inc.

http://feuerlabs.com

[Roberto Ostinelli]

Thank you Anthony, Ulf,

I'll definitely look into that. I just felt curious when I saw

-spec({{greetings, 1},

       [{type, 12, 'fun',

 [{type, 12, product,

   [{ann_type, 12,

     [{var, 12, 'Text'}, {type, 12, string, []}]}]},

  {type, 12, string, []}]}]}).

hem... ^^_

r.

[Roberto Ostinelli]

Thank you Ulf,

I've looked at this and it reads from .beam files. Same problem as before: as specified I need to parse string() code.

Do I really have to write my own erlang indenter? That really seems weird. Isn't there such a thing like a DSL for indenters?

On Tue, Sep 25, 2012 at 1:34 AM, Ulf Wiger <u...@feuerlabs.com> wrote:

[Ulf Wiger]

Someone really should fix the bugs in erl_prettypr.

BR,

Ulf W

Ulf Wiger, Feuerlabs, Inc.

http://www.feuerlabs.com

[Steve Davis]

I'd say someone decided to waste your brain-time. i.e. in making an apparent requirement of the -spec part of the code (as per the other thread I started).

 

Any input welcome.

r.