Operators

• addition, +
• subtraction or negative, -
• multiplication, *
• division, /
• integer division, // (divide then round down)
• remainder/modulo, %
• divisibility, %%. Returns true if the right operand evenly divides the left operand. (That is, a %% b is the same as a % b = 0)
• exponentiation, ^, e.g. a^3 raises a to the 3rd power.
• boolean operators, and, or, xor, not. Note that the and and or operators can short-circuit, i.e. given an expression a and b: if a is false, then the whole expression can never be true, so b is not even evaluated.
• bitwise operators, bitwise and, bitwise or, bitwise xor, bitwise not. Unlike the boolean operators, these do not short-circuit.
• comparison, >, >=, <, <=
• comparison (equality), =
• comparison (not equal), !=
• check for whether variables are set, exists (e.g. x exists)
• array slicing, :. Note that slices are inclusive of both their upper and lower bounds (e.g. 0:5 gives (0,1,2,3,4,5))
  • Slices may include an optional “step size”, e.g. 0:10:2 is read “0 to 10 step 2”, and gives (0,2,4,6,8,10).
  • When slicing an array or a string, it’s possible to replace the second number with a colon, to indicate that the slice should go from the start index all the way to the end of the string or array. So for example, "abcdef"[4::] would result in "def", (5,4,3,2,1)[2::] would result in (4,3,2,1), etc.
• array listing, , (e.g. 1,2,3 is an array with 3 elements, (1,) is an array with 1 element, (,) has 0 elements, etc). You can combine this with slicing, e.g. 1,3:5,9 gives (1,3,4,5,9).
• pattern matching, like, checks whether a string matches a given pattern (e.g. "123" like "%d+" gives true).
• array searching in (e.g. 3 in (1,2,4,5,6) gives false)
• string concatenation, & (e.g. "abc" & "def" gives "abcdef")
• ternary expression, val1 if expression else val2. Like Python’s ternary syntax, this will result in val1 if expression evaluates to true, otherwise it will result in val2.
• falsey fallback operator, val1 else val2. Results in val1 if val1 is truthy, otherwise results in val2. Syntax sugar for val1 if val1 else val2.
• truthy fallback operator, val1 then val2. Results in val2 if val1 is truthy, otherwise results in val1. Syntax sugar for val2 if val1 else val2.
• null fallback operator, val1 ?else val2. Results in val1 if val1 is not null, otherwise results in val2. Syntax sugar for val1 if val1 != null else val2.
• non-null fallback operator, val1 ?then val2. Results in val2 if val1 is not null, otherwise results in val1. Syntax sugar for val1 if val1 = null else val2.
• Indexing, []. Like most languages, this lets you get an element from a string, array, or object (e.g. "string"[2] gives “t”, ('a','b','c')[3] gives “c”, and ('a'=>'v1', 'b'=>'v2')['a'] gives “v1”), however Paisley also lets you select multiple items at once in a single index expression. E.g. "abcde"[2,5,5] gives “bee”, "abcde"[1:3] gives “abc”, (6,7,8,9,0)[3,1,5] gives (8,6,0).
• dot-notation, .. This is purely syntax sugar. When used with functions, the left side of the dot is treated as the first argument to the function, e.g. val1.func(val2, ...) = func(val1, val2, ...). When used with identifiers, a dot is shorthand for object indexing, e.g. obj.attr = obj["attr"].

Precedence

Operator precedence in Paisley follows the table below, from higher to lower priority:

. []
^
- not bitwise not (unary operators)
:
* / // % %%
+ -
> < >= <= = != in like not in not like
&
exists and or xor and any bitwise versions of the latter 4.
a for b in c a for b in c if d
a if b else c a else b  a ?else b a then b a ?then b
=>
,

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