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void -- type with no values

NOTE: For a counterpart to void in C, Java, etc., see unit.fz

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 := fuzion.std.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 generic argument for a generic feature. 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


and a pop function with a precondition that is always false

pop void
pre size > 0

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.