[hoytech]

> For example, in languages like Perl, JavaScript, and CoffeeScript adding a string to a number is permissible (e.g., "5" + 2 yields "52"). The same operation yields 7 in Php. Such an operation is not permitted in languages such as Java and Python as they do not allow implicit conversion.

Regarding Perl, the quoted statement is wrong:

    $ perl -E 'say "5" + 2'
    7

Furthermore, this is not an implicit conversion. The + operator is an explicit numeric conversion. Here's a more detailed description:

https://codespeaks.blogspot.ca/2007/09/ruby-and-python-overl...

[gipp]

Your link seems to argue that the simple fact that it's common convention makes it explicit, which doesn't really seem to hold water.

[hoytech]

Consider this javascript function:

    function add(a,b) { return a + b; }

Although no conversion is requested explicitly in the function definition, a conversion may take place depending on the types of the arguments passed in:

    > add(1,2)
    3
    >add("1",2)
    "12"

The article in question defines implicit conversion in this way, and in my experience it's a fairly common term.

I was pointing out that per this definition, the article is wrong in saying that perl's + operator may perform an implicit conversion. In perl the + operator always performs a numeric conversion of both its operands, regardless of types. By writing + you are explicitly requesting numeric conversion of both arguments.

In general perl doesn't perform implicit conversion (of course there are some exceptions -- it is perl after all). It does this by not overloading operators like + for different operations such as addition and concatenation.

This also has the nice property that you can count on a+b == b+a, unlike python for instance. (However, in python PEP-465, non-commutativity was a stated advantage of adopting @ for matrix multiplication instead of overloading *, go figure).

[agrafix]

The + operator is not an explicit numeric conversion. What numeric type is it converting to? In Python you can also combine two lists using the + operator.

Haskell for example requires to be explicit about this:

    y = (read "5" :: Int) + 5

[hoytech]

Please see my sibling reply. I was referring to perl, not python or haskell.