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new

mutate.new

(T 
type
:
Type, mutable_value T)
:
mutable_element,auto_unwrap T, mutate
 is
create a new mutable value with the given initial value and update the
'mutate' effect in the current environment

Type Parameters

Functions

 => 
String
[Redefinition of  Any.as_string]
returns `as_string` of the current value

redefines:

 => 
unit
[Inherited from  mutable_element]
stop any further mutations of this element
creates a copy of the mutable field
 => 
Type
[Inherited from  Any]
Get the dynamic type of this instance. For value instances `x`, this is
equal to `type_of x`, but for `x` with a `ref` type `x.dynamic_type` gives
the actual runtime type, while `type_of x` results in the static
compile-time type.

There is no dynamic type of a type instance since this would result in an
endless hierarchy of types. So for Type values, dynamic_type is redefined
to just return Type.type.
 => 
T
read the current value of this mutable value.

If this is open, check that the mutate effect this was created with is still
instated in the current environment.
infix operator for put, OCaml/F#-style syntax
 => 
bool
[Inherited from  mutable_element]
is this element open, i.e., can it be mutated?
 => 
String
[Inherited from  Any]
convenience prefix operator to create a string from a value.

This permits usage of `$` as a prefix operator in a similar way both
inside and outside of constant strings: $x and "$x" will produce the
same string.
(to T)
 => 
unit
update mutable field with new value

Check that the mutate effect this was created with is still
instated in the current environment.
 => 
T
[Redefinition of  auto_unwrap.unwrap]
unwrap this mutable value

redefines:

update mutable field using a function of the old value
 => 
T
read the mutable value that is now immutable after it was closed for mutation.

Type Functions

 => 
String
[Inherited from  Type]
string representation of this type to be used for debugging.

result has the form "Type of '<name>'", but this might change in the future

redefines:

 => 
Type
[Inherited from  Type]
There is no dynamic type of a type instance since this would result in an
endless hierarchy of types, so dynamic_type is redefined to just return
Type.type here.

redefines:

(T 
type
:
Type)
 => 
bool
[Inherited from  Type]
Is this type assignable to a type parameter with constraint `T`?

The result of this is a compile-time constant that can be used to specialize
code for a particular type.


it is most useful in conjunction with preconditions or `if` statements as in


or

 => 
String
[Inherited from  Type]
name of this type, including type parameters, e.g. 'option (list i32)'.
 => 
String
[Inherited from  Type]
convenience prefix operator to create a string from a value.

This permits usage of `$` as a prefix operator in a similar way both
inside and outside of constant strings: $x and "$x" will produce the
same string.

NYI: Redefinition allows the type feature to be distinguished from its normal counterpart, see #3913

redefines:

 => 
Type
[Inherited from  Any]
Get a type as a value.

This is a feature with the effect equivalent to Fuzion's `expr.type` call tail.
It is recommended to use `expr.type` and not `expr.type_value`.

`type_value` is here to show how this can be implemented and to illustrate the
difference to `dynamic_type`.
0.095dev (2025-08-15 12:02:22 GIT hash 301b5b75e77076d091b38f555473f9f0e31e5b5c built by fridi@fzen)
last changed: 2025-08-15