OpenEuphoria

Re: Comparing Sequences

• Posted by Al Getz <xaxo at AOL.COM> Oct 07, 2000
• 375 views

To Derek (and others):

Derek wrote:
>>
For example...

  function tester(atom X, atom Y)
      return (functionOne(X) = functionTwo(Y))
  end function

There is no way you can tell if this function returns an atom or a sequence,
unless you find out what functionOne() and functionTwo() return.

Is this a problem? Maybe, maybe not. Just thought I'd mention it though.
<<

 I've noticed this a long time ago, but it isnt an issue of comparison.

For example, take the same function 'tester' and simplify it:

  function tester(atom X)
      return functionOne(X)
  end function

and still cant tell what tester() returns.
I wont go as far as to say its a problem though, as it does allow one
to return 'objects', a 'feature' i wouldnt want to go without.

Second point:
  Some functions are better off with the ability to return an object,
rather then a particular sub type (atom, sequence).
For example:

  --Sqrt(object a) is a function that returns the sqrt of a number with
  -- real or complex result

  object x,a

  a=4
  x=Sqrt(a) --returns 2

  a= -4
  x=Sqrt(a) --returns {0,2}

  a={-3,4)
  x=Sqrt(a) --returns {1,2}

Here the return value depends on the users input and has to be
an atom or a sequence.  Thats one reason why i like to be able to
retain the ability to return objects.  I think this is an advanced
feature of the language.  True you could default to all sequences,
but i think then that would over-complicate the calculations on
simple numbers.

BTW im in favor of extending the syntax to allow comparisons on
sequences as well i.e.

 "Thisa"="Thata" returns false
 "Thisa"=This" returns false
 "This"="" returns false
 ""="" returns true
 {"This","That"}={"This"} returns false
 "A"={65} returns true
 'A'={65} returns false
 "AB"={65,66} returns true

  etc.

although i would like to see the double equal sign come in like other
languages:

  if "This"=="That" then
    dosomething()
  end if

making comparisons stand out from assignments a bit more.

--Al

ps. i should be posting a math library soon that has many more examples.