Operators
To get more complicated expressions you combine them using operators.
--Basic mathematics--
MSE script supports most basic mathamatical operators:
! Operator Example Description
| @a + b@ @3 + 2 == 5@
Add two numbers,
@"3" + "2" == "32"@ concatenate two strings or compose two functions (see below)
| @a - b@ @3 - 2 == 1@ Substract two numbers
| @a * b@ @3 * 2 == 6@ Multiply two numbers
| @a / b@ @3 / 2 == 1.5@ Divide two numbers. Does not round, always produces a [[type:double]].
| @a div b@ @3 div 2 == 1@ Divide two numbers. Rounds towards zero, producing an [[type:int]].
| @a mod b@ @3 mod 2 == 1@ Take the remainder after integer division (modulo)
| @-a@ @-(3 + 2) == -5@ Negate a number (make it negative if positive and vice versa)
===The + operator===
The @+@ operator has three functions
* It adds [[type:int]]s (also [[type:double]]s), @1+1 == 2@
* It concatenates strings, @"1" + "1" == "11"@
* It composes [[type:function]]s @(f + g) () == g( input: f() )@
--Comparison--
It is also possible to compare values. All comparisons evaluate to either @true@ or @false@.
! Operator Example Description
| @a == b@ @1 + 1 == 2@
@"x" == "x"@
@1 + 1 == "2"@ Are two numbers or strings the same? @=@ can also be used instead.
| @a != b@ @1 + 1 != 3@
@"x" != "y"@ Are two numbers or strings different?
| @a < b@ @1 < 2@
@"x" < "y"@ Is a less than b? Uses [[http://en.wikipedia.org/wiki/Lexicographical_order|lexicographic order]] for strings.
| @a > b@ @2 > 1@
@"y" > "x"@ Is a greater than b?
| @a <= b@ @1 <= 1@
@"x" <= "y"@ Is a less than b or are they equal?
| @a >= b@ @2 >= 1@
@"x" >= "x"@ Is a greater than b or are they equal?
| @min(a,b)@ @min(1,2) == 1@ Returns the smallest of two values.
| @max(a,b)@ @max(1,2) == 2@ Returns the largest of two values.
--Booleans--
[[type:Boolean]]s (for example from comparisons) can be combined using:
| @a and b@ Are both @a@ and @b@ true?
| @a or b@ Is at least one of @a@ and @b@ true?
| @a xor b@ Is exactly one of @a@ and @b@ true?
| @not a@ Is @a@ false?
In a table:
! @a@ @b@ a or b a and b a xor b
| @false@ @false@ @false@ @false@ @false@
| @false@ @true@ @true@ @false@ @true@
| @true@ @false@ @true@ @false@ @true@
| @true@ @true@ @true@ @true@ @false@
--Grouping and order--
Operators are ordered as usual, so
> 1 + 2 * 3 == 1 + (2 * 3) == 7
Operators can be grouped differently using parentheses.
> (1 + 2) * 3 == 3 * 3 == 9
The exact order of precedence is given in the following table,
higher in the table means that this operator binds tighter to its arguments, @*@ binds tighter then @+@.
| @a(...)@, @a.b@, @a[b]@ Function calls, property access, see below
| @-a@, @not@ Unary operators
| @*@, @/@, @div@, @mod@ Multiplication and division
| @+@, @-@ Addition and substraction
| @==@, @!=@, @<@, @>@, @<=@, @>=@ Comparisons
| @and@, @or@, @xor@ Boolean operators
| @:=@ Assignement, see below
| @;@ Sequence, see below
--Properties--
Properties of types, as described in the [[type:index|data type section]] of the documentation, can be accessed using the @.@ operator:
> set.cards # retrieve the 'cards' property of a set
The @[]@ operator has a similair purpose, only the property retrieved is determined by a string, so it can be changed:
> set["cards"] # same as above
> c := "cards"
> set[c] # again, the same
Multiple uses of these operators can be combined, for example:
> set.cards[0].card_color # the card color of the first card in the set
Note that a property named @card color@ is refered to as @card_color@ when using the @.@ operator, all spaces become underscores.
> style.padding left # syntax error
> style.padding_left # use this instead
--Assignment and sequence--
Values can be assigned to [[script:variables]] using the @:=@ operator:
> variable := 1 + 1
The result of this expression is the value assigned, this can be used to assign to multiple variables:
> var1 := var2 := 1 + 1
> # now var1 == 2 and var2 == 2
To combine multiple assignments into a single expression the ''sequencing operator'', @;@ can be used.
This first executes an expression, discards the result and then evaluates another one:
> var1 := 1 + 1 # assign
> ; # discard the result (i.e. 2)
> var1 * 2 # retrieve the value again, returns 4
Semicolons at the end of a line can be omitted, so the above can also be written simply as:
> var1 := 1 + 1
> var1 * 2