• Chris Piker (19/19) Sep 30 2023 Hi D
• Chris Piker (12/16) Sep 30 2023 I know it's bad form to reply to my own question, but I think I
• Paul Backus (4/23) Sep 30 2023 ```d
• Chris Piker (3/3) Sep 30 2023 We posted at the same time! Thanks for help nonetheless.

Chris Piker <chris hoopjump.com> writes:

Hi D

I've a simple question but it's bedeviling me anyway.  How do I 
get a string representation of the current type of a SumType?  
I'm trying to avoid something like this:

```d
alias Vec3 = SumType!(void* /* invalid vector */, byte[3], 
short[3], char[][3]);

string prnType(Vec3 vec){

   return vec.match!(
      (void* _) => "void*",
      (byte[3] _) => "byte[3]",
      (short[3] _) => "short[3]",
      (char[][3] _) => "char[][3]"
   );
}
```

I'm sure there's a much easier way, especially once there's a 
largish number of vector types.

Thanks,

Chris Piker <chris hoopjump.com> writes:

On Sunday, 1 October 2023 at 01:17:50 UTC, Chris Piker wrote:
 ```d
 alias Vec3 = SumType!(void* /* invalid vector */, byte[3], 
 short[3], char[][3]);

 ```


I know it's bad form to reply to my own question, but I think I 
found a reasonably simple way:

```d
string prnType(Vec3 vec){
    return vec.match!( t => typeof(t).stringof);
}
```

which is hardly worth making into a function of it's own.  Other 
suggestions are welcome of course.

SumTypes are really tripping me up.  Unlearning years of writing 
C takes more time then I'd prefer.

Paul Backus <snarwin gmail.com> writes:

On Sunday, 1 October 2023 at 01:17:50 UTC, Chris Piker wrote:
 Hi D

 I've a simple question but it's bedeviling me anyway.  How do I 
 get a string representation of the current type of a SumType?  
 I'm trying to avoid something like this:

 ```d
 alias Vec3 = SumType!(void* /* invalid vector */, byte[3], 
 short[3], char[][3]);

 string prnType(Vec3 vec){

   return vec.match!(
      (void* _) => "void*",
      (byte[3] _) => "byte[3]",
      (short[3] _) => "short[3]",
      (char[][3] _) => "char[][3]"
   );
 }
 ```

 I'm sure there's a much easier way, especially once there's a 
 largish number of vector types.

 Thanks,

```d
return vec.match(value => typeof(value).stringof);
```

Chris Piker <chris hoopjump.com> writes:

We posted at the same time!  Thanks for help nonetheless.

I do hope over time, SumTypes get the Ali Çehreli treatment.  I 
keep his book open on my desk all the time.