Haskell infix syntax

[Jacob Carlborg]

On 2011-03-07 01:10, Jonathan M Davis wrote:
> On Sunday 06 March 2011 10:03:05 Tomek Sowiński wrote:
>> bearophile bearophile napisał:
>>> Haskell is full of function calls, so the Haskell designers have
>>> used/invented several different ways to avoid some parenthesys in the
>>> code.
>>>
>>>  From what I've seen if you remove some parenthesis well, in the right
>>> places, the resulting code is less noisy, more readable, and it has less
>>> chances to contain a bug (because syntax noise is a good place for bugs
>>> to hide).
>>>
>>> One of the ways used to remove some parenthesys is a standard syntax
>>> that's optionally usable on any dyadic function (function with two
>>> arguments):
>>>
>>> sum a b = a + b
>>>
>>> sum 1 5 == 1 `sum` 5
>>>
>>> The `name` syntax is just a different way to call a regular function with
>>> two arguments.
>>>
>>> In Haskell there is also a way to assign an arbitrary precedence and
>>> associativity to such infix operators, but some Haskell programmers
>>> argue that too much syntax sugar gives troubles (
>>> http://www.haskell.org/haskellwiki/Use_of_infix_operators ).
>>>
>>> In D the back tick has a different meaning, and even if in D you use a
>>> different syntax, like just a $ prefix, I don't know how much good this
>>> syntax is for D:
>>>
>>> int sum(int x, int y) { return x + y; }
>>>
>>> int s = sum(1, sum(5, sum(6, sum(10, 30))));
>>> Equals to (associativity of $ is fixed like this):
>>> int s = 1 $sum 5 $sum 6 $sum 10 $sum 30;
>>>
>>> So I think it's not worth adding to D.
>>
>> I vaguely recall someone mentioned infixablility by naming convention.
>>
>> int _add_(int x, int y);
>>
>> int s = 1 _add_ 5 _add_ 10;
>>
>> As a feature of its own, it's just sugar. But if introducing infix
>> operators were contingent on banishing classic operator overloading, then
>> it is worthwhile.
>
> LOL. And _what_ benefit would banishing classic operator overloading have? A
> function named add could be abused in _exactly_ the same ways that + can be.

You could implement operator overloading without any special 
cases/support in the language, like Scala does. In Scala

3 + 4

Is syntax sugar for:

3.+(4)

It's possible because of the following three reasons:

* Everything is an object
* Method names can contain other characters than A-Za-z_
* The infix syntax discussed in this thread

Implementing operator overloading like this also allows you to add new 
operators and not just overloading existing ones.

-- 
/Jacob Carlborg