Function to print a diamond shape

[Ali Çehreli]

On 03/20/2014 03:03 PM, Brad Anderson wrote:

 > I'm not entirely happy with it but:

I am not happy with my attempt either. :)

 >    void main()
 >    {
 >      import std.algorithm, std.range, std.stdio, std.conv;
 >
 >      enum length = 5;
 >      auto rng =
 >         chain(iota(length), iota(length, -1, -1))

Ooh. I like that. That would have never occurred to me. :)

 >        .map!((a => " ".repeat(length-a)),
 >              (a => "#".repeat(a*2+1)))
 >        .map!(a => chain(a[0].joiner, a[1].joiner, "\n"))
 >        .joiner;
 >
 >      writeln(rng);
 >    }

Does that compile for you? Failed for me with v2.066-devel-d0f461a:

./phobos/std/typetuple.d(550): Error: template instance F!(__lambda1) 
cannot use local '__lambda1' as parameter to non-global template 
AppliedReturnType(alias f)
./phobos/std/typetuple.d(556): Error: template instance 
deneme.main.staticMap!(AppliedReturnType, __lambda1) error instantiating
./phobos/std/algorithm.d(404):        instantiated from here: 
staticMap!(AppliedReturnType, __lambda1, __lambda2)
deneme.d(161788):        instantiated from here: map!(Result)

That is pointing at this line:

         .map!((a => " ".repeat(length-a)),

A regression?

 > Had some trouble with the result coming out as integers instead of
 > something string-like.

I had the same problem at one point. I will try to understand when that 
happens.

Ali