# isimmutable

``````..  isimmutable(v)

Return ``true`` iff value ``v`` is immutable.  See :ref:`man-immutable-composite-types` for a discussion of immutability.
Note that this function works on values, so if you give it a type, it will tell you that a value of ``DataType`` is mutable.``````

## Examples

The `isimmutable` function in Julia is used to determine whether a given value is immutable or not. It returns `true` if the value is immutable, and `false` otherwise. Here are some examples of how to use the `isimmutable` function:

1. Check if an integer is immutable:

``````julia> isimmutable(5)
true``````

The `isimmutable` function returns `true` for immutable values like integers.

2. Check if a string is immutable:

``````julia> isimmutable("Julia")
true``````

Strings are immutable in Julia, so the `isimmutable` function returns `true` for them.

3. Check if an array is immutable:

``````julia> isimmutable([1, 2, 3])
false``````

Arrays are mutable in Julia, so the `isimmutable` function returns `false` for them.

4. Check if a custom composite type is immutable:

``````julia> struct Person
name::String
age::Int
end

julia> isimmutable(Person("Alice", 25))
false``````

Custom composite types are mutable by default unless explicitly defined as immutable. In this example, the `isimmutable` function returns `false` for the `Person` object.

Please note that the `isimmutable` function works on values, not types. If you provide a type to the function, it will tell you that a value of that type is mutable.

## See Also

BigFloat, BigInt, Dict, eltype, fieldtype, Float32, Float64, IntSet, isa, isalnum, isalpha, isascii, iseltype, isequal, isgraph, isimmutable, isinteractive, isleaftype, isnull, ispunct, isspace, issubtype, keytype, Nullable, NullException, promote_type, typeintersect, typejoin, typemax, typemin, typeof, Val, valtype,

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