D2 map trouble

[Nick Sabalausky]

"Nick Sabalausky" <a at a.a> wrote in message 
news:i2no7g$euv$1 at digitalmars.com...
> Trying to convert some D1 code to D2:
>
> On 2.047, I'm trying to do this:
>
> import std.string;
> void foo(string str)
> {
> str =
>  std.algorithm.map!(
>   (char a) { return inPattern(a, [digits, letters])? a : '_'; }
>  )(str);
> }
>
> And I'm getting:
>
> delegate std.algorithm.__dgliteral1 cannot access frame of function 
> __dgliteral1
>
> What's going on? How do I do it right? I figure I probably have some sort 
> of problem with strings being immutable(char)[] instead of char[], but it 
> doesn't look like that's the issue it's complaining about. Also, in this 
> particular case, I'm not concerned about multi-unit UTF-8 characters.
>
>

In my particular case, I've just switched to regex:

import std.regex;
str = replace(str, regex("[^a-zA-Z0-9]"), "_");

But I am still curious to hear what exactly was going on with map.