Why = = (and not just =)

[Thomas Mailund]

On Mon, 20 Oct 2003 00:59:30 +0200, Carlo v. Dango wrote:

>> expression syntax to boot. The original language in the Algol family,
>> Algol 60, used ":=" as the assignment operator as I recall, a tradition
>> followed by Pascal.
>>
>> Frankly, I'd rather have the assignment operator be something
>> like a left arrow: "<-" perhaps. I think it makes more sense,
>> and it avoids the confusion between one = and two.
> 
> actually Algol was meant to have the <- rather than the := but due to 
> problems writting the lexer/parser, it became :=
> 
> if you want a language which uses the <- operator then have a look at the 
> language "Beta" it takes a little getting used to, when used nested ;)
> 

Actually, if I recall correctly, BETA <URL:http://www.daimi.au.dk/~beta/>
uses the "->" operator--assignment goes the other way.

In BETA there's syntactical difference between assignment and equality
tests (= for testing equality, -> for assigning), but assignment and
method calls uses the same syntax.  So assigning to variable x, and
calling function f, uses the same operator:

  5 -> x; 5 -> f;


Just nitpicking...

	/mailund