[erlang-questions] erl_sytanx help

[Richard Carlsson]

This is a good opportunity to demonstrate the function erl_syntax:meta/1
(using merl in OTP 18 to simplify building the AST):

1> AST=merl:quote("-import(mymdule, [test1/0, test2/0])").
2> io:put_chars(erl_prettypr:format(erl_syntax:meta(AST))).

erl_syntax:make_tree(prefix_expr,
                     [[erl_syntax:operator('-')],
                      [erl_syntax:make_tree(application,
                                            [[erl_syntax:atom(import)],
                                             [erl_syntax:atom(mymdule),

erl_syntax:list([erl_syntax:make_tree(infix_expr,

[[erl_syntax:atom(test1)],

[erl_syntax:operator('/')],

[erl_syntax:integer(0)]]),

erl_syntax:make_tree(infix_expr,

[[erl_syntax:atom(test2)],

[erl_syntax:operator('/')],

[erl_syntax:integer(0)]])])]])]])

There's also the useful function merl:show/1 for inspecting the basic
structure of an AST:

3> merl:show(AST).

prefix_expr: -import(mymdule, [...])
  operator: -
  +
  application: import(mymdule, [test1 / 0, test2 / 0])
    atom: import
    +
    atom: mymdule
    list: [test1 / 0, test2 / 0]
      infix_expr: test1 / 0
        atom: test1
        +
        operator: /
        +
        integer: 0
      infix_expr: test2 / 0
        atom: test2
        +
        operator: /
        +
        integer: 0


    /Richard

On Tue, Jul 14, 2015 at 3:08 PM, Humberto Rodríguez Avila <
h87rguez@REDACTED> wrote:

> Hello guys!
>
>   I am a new programming in Erlang and I interested in doing things with
> meta-programming. I have been working with merl and I did a couple of
> examples (module generation). Nevertheless, I have been trying to do the
> same thing using erl_syntax, but I can’t found how to build the syntax
> tree of the directive -import :(
>
> For example:  -import(mymdule, [test1/0, test2/0])
>
> Any suggestion?
>
> Thanks in advance!
>
> --- Humberto
>
> _______________________________________________
> erlang-questions mailing list
> erlang-questions@REDACTED
> http://erlang.org/mailman/listinfo/erlang-questions
>
>
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