fix https://github.com/roogle-rs/roogle/issues/18

[asukaminato0721]

If I understand the parser correctly,

it doesn't support

type -> type

the bracket is necessary. As #5 said.

so I just change to multispace0.

the result:

curl -X GET \
  -d "fn(Option<Result<T, E>>) -> Result<Option<T>, E>>" \
                                         "localhost:8000/search?scope=set:libstd"
[{"name":"transpose","path":["core","option","Option","transpose"],"link":["core","option","enum.Option.html#method.transpose"],"docs":"Transposes an `Option` of a [`Result`] into a [`Result`] of an `Option`.\n\n[`None`] will be mapped to <code>[Ok]\\([None])</code>.\n<code>[Some]\\([Ok]\\(\\_))

and

curl -X GET \
 -d "fn (Option<Result<T, E>>) -> Result<Option<T>, E>>" \
                                         "localhost:8000/search?scope=set:libstd"
[{"name":"transpose","path":["core","option","Option","transpose"],"link":["core","option","enum.Option.html#method.transpose"],"docs":"Transposes an `Option` of a [`Result`] into a [`Result`] of an `Option`.\n\n[`None`] will be mapped to <code>[Ok]\\([None])</code>.\n<code>[Some]\\([Ok]\\(\\_))</code> 

so it seems work properly.

---

to fix the

fn(xx)
vs
fn f(xx)

I let the space before f, instead of after fn.

---

to fix #5, I guess add a alt may help.

or something like delimited( opt( char('(') ), xx , opt( char(')') ) )

[asukaminato0721]

this may have problem with fn f(xx) -> xx fixed.

[asukaminato0721]

@hkmatsumoto now it should work.

[hkmatsumoto]

LGTM, thanks!