Comments on: Learning Scala: Compiler Surprises http://villane.wordpress.com/2008/01/11/learning-scala-compiler-surprises/ Thoughts on software development Tue, 29 Sep 2009 10:27:34 +0000 http://wordpress.com/ hourly 1 By: Scala: for a/vs while « Villane http://villane.wordpress.com/2008/01/11/learning-scala-compiler-surprises/#comment-16 Scala: for a/vs while « Villane Wed, 06 Feb 2008 23:49:53 +0000 http://villane.wordpress.com/2008/01/11/learning-scala-compiler-surprises/#comment-16 [...] comes from by examining what the library code and the compiler actually do here, as I did in a previous post. The imperative style while expression will be compiled into some pretty efficient byte-code, which [...] [...] comes from by examining what the library code and the compiler actually do here, as I did in a previous post. The imperative style while expression will be compiled into some pretty efficient byte-code, which [...]

]]> By: Learning Scala: Performance Impact of Implicit Conversions « Villane http://villane.wordpress.com/2008/01/11/learning-scala-compiler-surprises/#comment-14 Learning Scala: Performance Impact of Implicit Conversions « Villane Sat, 02 Feb 2008 16:46:29 +0000 http://villane.wordpress.com/2008/01/11/learning-scala-compiler-surprises/#comment-14 [...] great tool for enhancing classes coming from libraries that you can’t just change yourself. I went into details on how it works a few weeks ago. With implicit conversions it can be made to appear that methods [...] [...] great tool for enhancing classes coming from libraries that you can’t just change yourself. I went into details on how it works a few weeks ago. With implicit conversions it can be made to appear that methods [...]

]]> By: Stefan Zeiger http://villane.wordpress.com/2008/01/11/learning-scala-compiler-surprises/#comment-10 Stefan Zeiger Fri, 11 Jan 2008 23:17:27 +0000 http://villane.wordpress.com/2008/01/11/learning-scala-compiler-surprises/#comment-10 I just checked the first edition of the JLS. It's always been the same but it turns out my earlier description was wrong, too. In fact, '+' operators are evaluated strictly from left to right with no look-ahead to detect string concatenation. But string concatenation occurs when *either* the left or right hand operand is a string. That's why the 1 + " minute" -> "1 minute" example works. "foo" + 1 + 2 also gives the expected result "foo12" but 1 + 2 + "foo" gets evaluated as (1 + 2) + "foo" and gives the result "3foo". The somehwat ugly workaround "" + 1 + 2 + "foo" enforces a string concatenation so you get "12foo". I don't think I have ever encountered such a situation (with 2 non-string objects at the beginning of a string concatentation) in all my years of Java programming. I just checked the first edition of the JLS. It’s always been the same but it turns out my earlier description was wrong, too. In fact, ‘+’ operators are evaluated strictly from left to right with no look-ahead to detect string concatenation. But string concatenation occurs when *either* the left or right hand operand is a string. That’s why the 1 + ” minute” -> “1 minute” example works. “foo” + 1 + 2 also gives the expected result “foo12″ but 1 + 2 + “foo” gets evaluated as (1 + 2) + “foo” and gives the result “3foo”. The somehwat ugly workaround “” + 1 + 2 + “foo” enforces a string concatenation so you get “12foo”.

I don’t think I have ever encountered such a situation (with 2 non-string objects at the beginning of a string concatentation) in all my years of Java programming.

]]> By: Erkki Lindpere http://villane.wordpress.com/2008/01/11/learning-scala-compiler-surprises/#comment-9 Erkki Lindpere Fri, 11 Jan 2008 21:00:43 +0000 http://villane.wordpress.com/2008/01/11/learning-scala-compiler-surprises/#comment-9 Thanks for pointing that out. For some reason I have never noticed this feature about Java and remember seeing code like "" + 1 + ... . Has it always been like this? Thanks for pointing that out. For some reason I have never noticed this feature about Java and remember seeing code like “” + 1 + … . Has it always been like this?

]]> By: szeiger http://villane.wordpress.com/2008/01/11/learning-scala-compiler-surprises/#comment-8 szeiger Fri, 11 Jan 2008 20:35:12 +0000 http://villane.wordpress.com/2008/01/11/learning-scala-compiler-surprises/#comment-8 Actually, the string concatenation is just as easy in Java: String s = 1 + " minute"; Chained "+" operations are always considered as a whole and if there is at least one operand of type String, a string concatenation is performed. Actually, the string concatenation is just as easy in Java:

String s = 1 + ” minute”;

Chained “+” operations are always considered as a whole and if there is at least one operand of type String, a string concatenation is performed.

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