[Haskell-beginners] Haskell as a useful practical 'tool' for intelligent non-programmers

[Michael Orlitzky]

On 04/28/2012 10:37 PM, Lyndon Maydwell wrote:
> Your first example is not behaving how you think it is...
> 
> 
> ruby-1.9.2-p0 :012 > def foo
> ruby-1.9.2-p0 :013?>   puts "foo"
> ruby-1.9.2-p0 :014?> end
>  => nil
> ruby-1.9.2-p0 :015 > def call_arg(f)
> ruby-1.9.2-p0 :016?>   puts "calling"
> ruby-1.9.2-p0 :017?>   f
> ruby-1.9.2-p0 :018?> end
>  => nil
> ruby-1.9.2-p0 :019 > call_arg(foo)
> foo
> calling
>  => nil
> 
> Note that "foo" is printed before "calling".
> 

Indeed, I tried to make the example cute and botched it. This should be
less screwupy (you have to desugar the 'def...' to make it work properly).

  foo = Proc.new { puts "foo" }
  bar = lambda { puts "bar" }

  def baz
    puts "baz"
  end

  def call_arg(f)
    puts "before call"
    f.call()
    puts "after call"
  end

  call_arg(foo)
  puts ""
  call_arg(bar)
  puts ""
  call_arg(method(:baz))