Something New With Ruby

####Lambda Literals

succ = lambda {|x| x+1}
succ = ->(x){ x+1 }
succ = ->x { x+1 }

####Porc Equality

lambda {|x| x+1 } == lambda {|x| x+1 } # false

p = lambda {|x| x+1 }
q = p.dup
p == q #true
p.object_id == q.object_id #false

####Shorthand for string list

%w{word1 word2 etc}

####Warning Mode

irb -w
ruby -w

####Annotation

• TODO
• FIXME

• OPTIMIZE

  rake notes

####Hash

Basically use fetch instead of square brackets- it will raise error if it’s nil.

####String

Flexible quoting:

• $(string)
• %!string!
• %{string}

Shovel(«) operator modifies the original string, while += doesn’t

####Symbol

String.to_sym

I/O

$stdout.reopen 'filename' # redirect standard ouput to a file
$stdin.noecho &:gets # runs gets without echoing input to the screen
$stdin.reopen '/dev/tty' # redirect standard output to the terminal

####Questions?

arr = [1,2,3,4] why arr[4..0] == [] but arr[5..0] == nil

what’s with single quotes sometimes interpret escape characters

@about_symbols.rb:34

@about_constants.rb:87