Fun with yield

[haskell]

yield is possibly one of Ruby's most powerful features. It basically allows you to put a block of code into a function.

This could be a value, a string, a regex, function call, etc...

Consider:

Ruby:

def dynamic_square   return yield * yield end

Ruby:

puts dynamic_square { 6 }

Which results in 36.

Or:

Ruby:

def vowel_replace   line = yield     if line =~ /a|e|i|o|u/     line = line.gsub(/a|e|i|o|u/, 'Y')   end   result = line end

Ruby:

puts vowel_replace {"The quick brown fox jumped over the lazy dog"}

Which results in "ThY qYYck brYwn fYx jYmpYd YvYr thY lYzy dYg".

Ruby:

def lambda   return yield end

Ruby:

lambda do   puts "Omg! Stealing from Lisp!!"                      end

Ruby:

lambda do   puts "Lisp snatching again\n" * 10 end

Trivial examples. But they show a potential(particularly in AI).

So go off and experiment!

[rdrake]

haskell wrote:

Consider:

Ruby:

def dynamic_square   return yield * yield end

Ruby:

puts dynamic_square { 6 }

Which results in 36.

Remember in Ruby the last value evaluated will also be the result returned by default.

Consider:

Ruby:

def dynamic_square   yield * yield end

Ruby:

> dynamic_square { 6 } => 36

[wtd]

code:

def vowel_replace   line = yield     if line =~ /a|e|i|o|u/     line = line.gsub(/a|e|i|o|u/, 'Y')   end   result = line end

How about...

code:

def vowel_replace   yield.gsub(/a|e|i|o|u/, 'Y') end

[rdrake]

wtd wrote:

How about...

code:

def vowel_replace   yield.gsub(/a|e|i|o|u/, 'Y') end

Or...

code:

irb(main):003:0> def vowel_replace (letter) irb(main):004:1>   yield.gsub(/a|e|i|o|u/, letter) irb(main):005:1> end => nil irb(main):007:0> vowel_replace('y'){"hello"} => "hylly"

[haskell]

Passing Values to Block Using yield

Ruby:

def pass_name   puts "What is your name?\n"   n = gets   yield(n) end

Ruby:

pass_name do  |name|                            puts("Hello, \n " + name)           end

Which can also be dome as:

Ruby:

pass_name do  |name|                            puts "Hello, \n #{name}"           end

As you can see, the variable n of the pass_name method was passed to the block(do..end), and then used(under the new name, name, denoted by the | and | to be a variable of the block).

The block could also have been done with brackets({ and }) instead of do ..end, but it is multi-lined, so do..end is the "standard".

Have fun, and experiment .

[wtd]

haskell wrote:

Passing Values to Block Using yield

Ruby:

def pass_name   puts "What is your name?\n"   n = gets   yield(n) end

Or just:

code:

def pass_name    puts "What is your name?"    yield gets end

I also find it mildly odd that you're not aware that "puts" automatically adds a newline as necessary. In your code, the newline you use is extraneous.

[haskell]

I am aware. I just prefer to be explicit with my intentions. It doesn't make any difference in the output, but I know exactly what it will do without thinking about the function call(old habits die hard).

I also use extra vars in the examples to show how vars can be passed using yield. Its not the passing of gets thats important in this example(thanks for the extra examples though).

[Clayton]

okay, but afterwards, show how that can be streamlined by getting rid of uneeded "stuff". Follow this trivial example:

Ruby:

def is_odd?(number)     if number % 2 == 1 then         true     else         false     end end

Can be shortened to:

Ruby:

def is_odd?(number)     number % 2 == 1 end

Now, from a beginner's standpoint, the first makes more sense right? That's great, but they probably know that there has to be a better way of doing things, so then you show them, with the explanation of why it works exactly why it does.