Ruby Blocks and Blocks


Category: Code
Tags: Ruby    design   functional programming   pointfree  

I’m reading Programming Ruby: 2nd Ed. and an example on page 57 has captured my attention. (Code slightly modified for brevity)

` “3 4\n5 6\n7 8”.each do line v1, v2 = line.split print Integer(v1) + Integer(v2), “ “ end `{lang=”ruby”}

The book is just explaining to Perl coders that you have to call Integer() to convert strings to ints, but I see an interesting opportunity to restructure the code.

` “3 4\n5 6\n7 8”.collect do line line.split end.each do a, b print Integer(a) + Integer(b), “ “ end `{lang=”ruby”}

My brain is nagging me that there’s a fundamental concept at work in this change, but I can’t quite put my finger on it. It’s not just that I’m building an array in the middle or that it evaluates differently (after producing identical output), it’s that it looks something like nested fuction calls. It feels like a more a functional style of programming, but that’s not quite all.

I’m compelled to write this as a block yielding to a block, though it doesn’t compile:

` “3 4\n5 6\n7 8”.collect { line yield line.split } { a, b print Integer(a) + Integer(b), “ “ } `{lang=”ruby”}

Any thoughts? Am I just being weird, or can anyone put better words to it?