forward-reference

I'm trying to compile the following code, using Scala 2.11.7. object LucasSeq { val fibo: Stream[Int] = 0 #:: 1 #:: fibo.zip(fibo.tail).map { pair => pair._1 + pair._2 } def firstKind(p: Int, q: Int): Stream[Int] = { val lucas: Stream[Int] = 0 #:: 1 #:: lucas.zip(lucas.tail).map { pair => p * pair._2 - q * pair._1 } lucas } } fibo is based on the Fibonacci sequence example in Scala's Stream documentation , and it works. However, the firstKind function, which tries to generalize the sequence with parameters p and q (making Lucas sequences of the first kind ), has the following error: LucasSeq

When I use the this keyword for accessing a non-static variable in a class, Java doesn't give any error. But when I don't use it, Java gives an error. Why must I use this ? I know when should normally I use this , but this example is very different from normal usages. Example: class Foo { // int a = b; // gives error. why ? int a = this.b; // no error. why ? int b; int c = b; int var1 = this.var2; // very interesting int var2 = this.var1; // very interesting } Jason Variables are declared first and then assigned. That class is the same as this: class Foo { int a; int b; int c = b; int var1;

What is forward reference in C with respect to pointers? Can I get an example? strager See this page on forward references . I don't see how forward referencing would be different with pointers and with other PoD types. Note that you can forward declare types, and declare variables which are pointers to that type: struct MyStruct; struct MyStruct *ptr; struct MyStruct var; // ILLEGAL ptr->member; // ILLEGAL struct MyStruct { // ... }; // Or: typedef struct MyStruct MyStruct; MyStruct *ptr; MyStruct var; // ILLEGAL ptr->member; // ILLEGAL struct MyStruct { // ... }; I think this is what you're