Multiple assignment using array matching does not work with uppercase letters

Question

After reading this answer, I tried to play with this pleasant opportunity myself and found out that this is normal when I do

scala> val Array(a,b,n) = "XXX,YYY,ZZZ".split(",") a: java.lang.String = XXX b: java.lang.String = YYY n: java.lang.String = ZZZ 

But this is not normal with a uppercase named variable:

 scala> val Array(a,b,N) = "XXX,YYY,ZZZ".split(",") <console>:9: error: not found: value N val Array(a,b,N) = "XXX,YYY,ZZZ".split(",") 

What is the reason for this behavior?

UPD Actually, the same thing with binding tuples:

 scala> val (a,b,N) = (1,2,3) <console>:9: error: not found: value N val (a,b,N) = (1,2,3) 

Answer 1

Scala treats it as a constant against which the pattern matches. Note:

 scala> val N = 20 N: Int = 20 scala> val Array(a, b, N) = Array(11, 23, 20) a: Int = 11 b: Int = 23 scala> val Array(a, b, N) = Array(11, 23, 21) scala.MatchError: [ I@195d471 (of class [I) at .<init>(<console>:75) at .<clinit>(<console>) at .<init>(<console>:11) at .<clinit>(<console>) at $print(<console>) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at scala.tools.nsc.interpreter.IMain$ReadEvalPrint.call(IMain.scala:704) at scala.tools.nsc.interpreter.IMain$Request$$anonfun$14.apply(IMain.scala:920) at scala.tools.nsc.interpreter.Line$$anonfun$1.apply$mcV$sp(Line.scala:43) at scala.tools.nsc.io.package$$anon$2.run(package.scala:25) at java.lang.Thread.run(Thread.java:662) 

The variables in which you want to extract the values ​​must begin with a lowercase letter.