☰
void
void
Functions
create a String from this instance. Unless redefined, `a.as_string` will
create `"instance[T]"` where `T` is the dynamic type of `a`
create `"instance[T]"` where `T` is the dynamic type of `a`
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.
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.
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.
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.
Type Features
string representation of this type to be used for debugging.
result has the form "Type of '<name>'", but this might change in the future
result has the form "Type of '<name>'", but this might change in the future
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.
endless hierarchy of types, so dynamic_type is redefined to just return
Type.type here.
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.
is_of_integer_type(n T : numeric) => T : integer
say (is_of_integer_type 1234) # true
say (is_of_integer_type 3.14) # false
it is most useful in conjunction preconditions or `if` statements as in
pair(a,b T) is
=>
or
val(n T) is
The result of this is a compile-time constant that can be used to specialize
code for a particular type.
is_of_integer_type(n T : numeric) => T : integer
say (is_of_integer_type 1234) # true
say (is_of_integer_type 3.14) # false
it is most useful in conjunction preconditions or `if` statements as in
pair(a,b T) is
=>
or
val(n T) is
name of this type, including type parameters, e.g. 'option (list i32)'.
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`.
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`.
NOTE: For a counterpart to void in C, Java, etc., see unit.fz
void is the bottom type in Fuzion, the default empty type that is a subtype of all
other types.
It is impossible to create any values of this type, consequently, it is impossible
to assign anything to a field of void type.
If used as the type of an argument field for a feature, the feature can never be
called since no value assignable to that argument could ever be produced. This
produces an absurd feature.
If used as the result type of a routine, the routine can never return.
void is the result type of the endless loop
do { <loop body> }
If used as the result type of a field, the field can never be assigned a value,
since no such value can be produced, and the field can never be read since it
remains not initialized forever.
Type void is assignable to all other types, e.g, we can assign void to a value
of type i32:
i i32 := exit 1
Since no value of type void can ever be produced, the assignment is dead code that
will be removed by the fuzion implementation.
Type void may be used as an actual type argument for a type parameter. If this
is done, it will turn all features that have arguments of that type into absurd
features. Also, this will ensure that any feature that produces a result of that
type to never return a result (typically to not be callable in the first place as
well). An example could be a stack of capacity zero: stack void 0 with an
absurd
stack.push(void)
and a pop function with a precondition that is always false
pop void
The memory required to store a value of void type is not defined since these
values do not exist. The Fuzion code generators typically will not generate
any code for features receiving arguments of void type or for code following
a feature call that returns void.