• Lutger (18/18) Sep 01 2016 I was looking for something like FirstOrDefault* from .NET in
• Cauterite (4/4) Sep 02 2016 On Friday, 2 September 2016 at 06:56:07 UTC, Lutger wrote:
• Nicholas Wilson (8/26) Sep 02 2016 ElementType!R firstOrDefault(R)(R r, ElementType!R def =

Lutger <lutger.blijdestijn gmail.com> writes:

I was looking for something like FirstOrDefault* from .NET in 
phobos. For example, I have this piece of code:

string findBobOrReturnNull(string[] names)
{
     auto r = names.find("bob");
     if(r.empty) return null;
     return r.front;
}

assert(findBobOrReturnNull(["alice", "bob"]) == "bob");
assert(findBobOrReturnNull(["alice"]) is null);

How can I turn that into something like this, or is there another 
idiomatic way to write it as a single expression?

string findBobOrReturnNull(string[] names)
{
     return names.find("bob").firstOrDefault;
}

* 
https://msdn.microsoft.com/en-us/library/bb340482%28v=vs.110%29.aspx

Cauterite <cauterite gmail.com> writes:

On Friday, 2 September 2016 at 06:56:07 UTC, Lutger wrote:

You could do:
names.find("bob").chain(only(``)).front;
It's not very expressive though.

Nicholas Wilson <iamthewilsonator hotmail.com> writes:

On Friday, 2 September 2016 at 06:56:07 UTC, Lutger wrote:
 I was looking for something like FirstOrDefault* from .NET in 
 phobos. For example, I have this piece of code:

 string findBobOrReturnNull(string[] names)
 {
     auto r = names.find("bob");
     if(r.empty) return null;
     return r.front;
 }

 assert(findBobOrReturnNull(["alice", "bob"]) == "bob");
 assert(findBobOrReturnNull(["alice"]) is null);

 How can I turn that into something like this, or is there 
 another idiomatic way to write it as a single expression?

 string findBobOrReturnNull(string[] names)
 {
     return names.find("bob").firstOrDefault;
 }

 * 
 https://msdn.microsoft.com/en-us/library/bb340482%28v=vs.110%29.aspx

ElementType!R firstOrDefault(R)(R r, ElementType!R def = 
(ElementType!R).init)
        if(isInputRange!R)
{
     if(r.empty) return def;
     return r.front;
}