Does anyone know some background, why Scala and C# use double arrow (=>) for lambdas instead of single arrow (->)?
Single arrow is more common in literature, is used in Haskell, O'Caml, F#, Groovy etc. and IMO it also looks nicer :)
+13
A:
In C#,
maybe because -> operator is already used in case of unsafe code (LINK)
digEmAll
2010-09-02 17:39:30
this makes perfectly sense!
Aivar
2010-09-02 17:44:08
I'm pretty sure the influence of other functional languages had a larger part to play in Scala's design. C# is definitely not the reason, the fact that C# has the => syntax as well could just as easily have the same reasoning.
gpampara
2010-09-02 19:45:38
+6
A:
In Scala, there is also the "map arrow" that indicates a mapping from an item a to another b. Using => for lambdas frees up -> for things like Map(1 -> "One", 2 -> "Two"), and as others have pointed out the => is not unique to C# and Scala.
Rex Kerr
2010-09-02 18:23:50
Of course, you could also reason that if they had used the `=>` map arrow from Perl, that would have freed-up the `->` arrow for lambdas.
Gabe
2010-09-03 07:29:46
+1
A:
you might be interested to know that in Scala you can use the unicode equivalent for => as well as other arrows: http://scala-programming-language.1934581.n4.nabble.com/More-unicode-alternatives-for-ASCII-operators-td2008146.html
Channing Walton
2010-09-02 21:08:04
+6
A:
Pizza, which was sort of a predecessor for Scala had -> in function types. I remember that C++ programmers were baffled by this choice of symbol. That's the primary reason why Scala chose => AFAIRC. It seems the C# guys went through the same reasoning.
Martin Odersky
2010-09-03 07:13:50
Well, the C# guys couldn't use the `->` arrow because it means the same thing in C# that it does in C++. Since Pizza and Scala don't have the pointer dereference operator, it's not quite the same reasoning.
Gabe
2010-09-03 07:31:08