Perl - the Detroit of scripting languages

Re:Perl - the Detroit of scripting languages by marpmarpmar on Wednesday July 31, 2013 @03:57PM (#6136445)

You're right. I did not explain that well enough. Even with sigils it is unclear whether qv_mult will take 1 or 2 arguments, or whether qq_mult will take 1, 2 or 3. What is however clear is that only qq_mult and qv_mult are function calls, which it previously was not. Worse, what i did not mention then: When reading carefully it was easy to tell that they had to be function calls; however it was impossible to tell whether the two quaternions and the vector were variables, or function calls that did not take any arguments. Only with sigils becomes this clear.

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Re:Perl - the Detroit of scripting languages by TylerE on Wednesday July 31, 2013 @04:19PM (#6136563)

I'm still unclear on what the dataflow is... is w set to the value of the qq_mult call and the rest just executed for side effects?

Regardless, please defend how that is not just an improvement over, but better than, say:

    my $W = qq_mult $ConjugateQ, qv_mult $RotationQ, $Vector;

    w = qq_mult(qv_mult(CondugateQ, Vector))

or whatever the precedence and dataflow semantics are

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Re:Perl - the Detroit of scripting languages by marpmarpmar on Wednesday July 31, 2013 @04:31PM (#6136638)

That example doesn't show it very well. To be clear: The intended advantage is: Parens are optional. That permits syntax like the following to be implemented in pure Perl without changing the parser:

    try {
        die "foo";
    }
    catch {
        warn "caught error: $_";
    };

If parens were mandatory, it would need look like this:

    try(
        sub {
            die "foo";
        }
        catch(
            sub {
                warn "caught error: $_";
            }
        )
    );

Having the nicer form in the first example is possible only because sigils are mandatory, along with auto-flattening variables and easy code highlighting.

As for the example, with mandatory parens it would look like this:

    w = qq_mult( ConjugateQ, qv_mult( RotationQ, Vector ) );

In production i'd write it like this:

    my $W = qq_mult $ConjugateQ, qv_mult( $RotationQ, $Vector );

That gives a nice balance between a low number of parens, and clarity of intent.

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