"string_to_term/1"？

Question

Erlang中是否有这种行为的函数？:

a_function_id_like_to_have("{1,2,{3,4}}") % => {1,2,{3,4}}

(就像read在Haskell中一样)

Answer 1

看一下这个演示文稿的幻灯片25 .

它利用的erl_eval,erl_parse和erl_scan.

1> {ok, Tokens, _} = erl_scan:string("{1,2,{3,4}}.").
{ok,[{'{',1},
     {integer,1,1},
     {',',1},
     {integer,1,2},
     {',',1},
     {'{',1},
     {integer,1,3},
     {',',1},
     {integer,1,4},
     {'}',1},
     {'}',1},
     {dot,1}],
    1}
2> {ok, Abstract} = erl_parse:parse_exprs(Tokens).
{ok,[{tuple,1,
            [{integer,1,1},
             {integer,1,2},
             {tuple,1,[{integer,1,3},{integer,1,4}]}]}]}
3> Bindings = erl_eval:new_bindings().
[]
4> {value, Value, _} = erl_eval:exprs(Abstract, Bindings).
{value,{1,2,{3,4}},[]}
5> erlang:display(Value).
{1,2,{3,4}}
true