funq: syntax that doesn't scare off C++ developers

[Ivan Čukić]

> undefined = defined -> returns true, has a sideeffect: the variable that was
> undefined gets assigned the value of defined

This should not be seen as a statement at all - so it should not return 
anything. It just defines a substitution value for a specific name. 

That is,
  x = 2; x * x;
does not mean, create a variable x, set its value to 2, and return x*x;

It means x in the formula x*x is the value of 2. Return 2*2.

Here we come to purity of the language. That is, are 
    f(x) + f(x)
and
    y = f(x);
    y + y;
and
    2 * f(x)
equivalent.

Aaron said that we don't want to be totally pure, but in that case we need to 
make a distinction between pure parts and impure ones. If we can count on f in 
above example to be pure, then we can do a graph redux and evaluate f(x) only 
once. (which would make the above examples equivalent.
  

Cheerio,
Ivan


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