Question

I very rarely meet any other programmers!

My thought when I first saw the token was ‘implies that’ since that’s what it would read it as in a mathematical proof but that clearly isn’t its sense.

So how do I say or read ‘=>’ as in:-

IEnumerable<Person> Adults = people.Where(p => p.Age > 16) 

Or is there even an agreed way of saying it?

Answer 1

I usually say ‘such that’ when reading that operator.

In your example, p => p.Age > 16 reads as ‘P, such that p.Age is greater than 16.’

In fact, I asked this very question on the official linq pre-release forums, and Anders Hejlsberg responded by saying

I usually read the => operator as ‘becomes’ or ‘for which’. For example,
Func f = x => x * 2;
Func test = c => c.City == ‘London’;
reads as ‘x becomes x * 2’ and ‘c for which c.City equals London’

As far as ‘goes to’ – that’s never made sense to me. ‘p’ isn’t going anywhere.

In the case of reading code to someone, say, over the phone, then as long as they’re a fellow C# programmer, I’d just use the word ‘lambda’ – that is, ‘p lambda p dot age greater-than sixteen.’

In comments Steve Jessop mentioned ‘maps to’ in the case of transformations – so taking Anders’ example:

x => x * 2; 

would read

x maps to x times 2.

That does seem much closer to the actual intention of the code than ‘becomes’ for this case.