Overloaded operators: Difference between revisions
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→{{header|Raku}}: Add some verbiage about precedence and symbol reuse
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While it is very easy to overload operators in Raku, it isn't really common...
at least, not in the traditional sense. Or it's extremely common... It depends on how you view it.
First off, do not confuse "symbol reuse" with operator overloading. Multiplication * and exponentiation ** operators both use an asterisk, but one is not an overload of the other. A single asterisk is not the same as two. In fact the term * (whatever) also exists, but differs from both. The parser is smart enough to know when a term or an operator is expected and will select the correct one (or warn if they are not in the correct position).
For example:
<lang perl6>1, 2, 1, * ** * * * … *</lang>
is a perfectly cromulent sequence definition in Raku. A little odd perhaps, be completely sensible. (It's the sequence starting with givens 1,2,1, with each term after the value of the term 3 terms back, raised to the power of the term two terms back, multiplied by the value one term back, continuing for some undefined number of terms. - Whatever to the whatever times whatever until whatever.)
One of the founding principles of Raku is that: "Different things should look different". It follows that "Similar things should look similar".
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3.00.5e1
2 3 45 6 # default stringification, then concatenate</pre>
There is nothing preventing you from overloading or overriding existing
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prefix, postfix, (or post-circumfix!) The precedence, associativity and arity
are all easily defined. An operator at heart is just a subroutine with funny calling conventions.
Borrowed from the [[Nimber_arithmetic#Raku|Nimber arithmetic]] task:
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<pre>31562</pre>
Base Raku has 27 different operator precedence levels for built-ins. You could theoretically give a new operator a absolute numeric precedence but it would be difficult to predict exactly what the relative precedence would be. Instead, precedence is set by setting a relative precedence; either equivalent to an existing operator, or, by setting it tighter(higher) or looser(lower) precedence than an existing operator. When tighter or looser precedence is specified, a whole new precedence level is created squeezed in between the named level and its immediate successor (predecessor). The task [[Exponentiation_with_infix_operators_in_(or_operating_on)_the_base#Raku|Exponentiation with infix operators in (or operating on) the base]] demonstrates three different operators that nominally do the same thing, but may yield different results due to differing precedence levels.
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