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tuple

tuple

(A 
type
..., values A...)
:
orderable,hashable
 is
tuple -- feature used to define tuple types

tuple types provide algebraic product types of all the generic arguments
provided to tuple.

The values within a tuple 'tuple A B C' can be accessed via the tuple's
argument field 'values' followed by a selector referring to the generic
argument's position: 'values.0', 'values.1' and 'values.2', respectively.

Syntactic sugar of the Fuzion language permits an alternative notation
to create values of tuple types as follows


is equivalent to


The actual generic types are inferred from the static types of the values
'a', 'b', 'c', ... the tuple is created from.

Similarly, syntactic sugar for the destructuring of tuples can be used
to access the values as in


In destructurings, we can denote values we are not interested in using
'_' as in

(_, b) := ("first", "second")

which will set 'b' to '"second"' and drop the first element of the tuple.

As an example, say we want to identify a person by its name and its age,
so we can define


Then, we could extract Bob's age using


or Claire's name using


Destructuring also works for general features, e.g.


and the destructured value can then be used to create a tuple


however, tuples are not assignment compatible with general features even
if they would destructure into the same types, i.e.,


The unit tuple '()' can be used as a short-hand to create the empty tuple
'tuple'. The empty tuple can be destructured like any other tuple
using


even though this has no effect.

An instance of the single tuple 'tuple A' with sole element 'a' can not
be created using syntactic sugar '(a)', this will produce the plain
value of 'a' instead. However, destructuring of a single tuple is possible:

(a0) := tuple a

which is equivalent to


NYI: A single tuple 'tuple A' is currently not assignment compatible with
type 'A', which would make handling of general tuples easier.

tuples and destructuring can be used to swap two elements or create a
permutation as in


A tuple type with no actual generic arguments is isomorphic to 'unit', i.e, it
is a type that has only one single value: '()'.

Type Parameters

Fields

values
 A...

Functions

 => 
String
[Redefinition of  Any.as_string]
create a String from this instance.

redefines:

(R 
type
, F 
type
: Typed_Function R, f F)
 => 
R
[Inherited from  Any]
dynamic_apply -- apply `f.call` to `Any.this`'s dynamic type and value

This can be used to perform operation on values depending on their dynamic
type.

Here is an example that takes a `Sequence Any` that may contain boxed values
of types `i32` and `f64`. We can now write a feature `get_f64` that extracts
these values converted to `f64` and build a function `sum` that sums them up
as follows:


NYI: IMPROVEMENT: #5892: If this is fixed, we could write

 => 
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.
 => 
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.

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:

(a tuple.this.type, b tuple.this.type)
 => 
bool
equality of two tuple `a` and `b` is defined only if all elements of the tuple
are equatable and all elements are equal.

This will result in a runtime `panic` in case any element type is not equatable.
(a tuple.this.type)
 => 
u64
create hash code for this tuple

This should satisfy the following condition:

(T.equality a b) : (T.hash_code a = T.hash_code b)

This will result in a compile-time `panic` in case any element type is not hashable.

The algorithm used here is a variation of (XXXHash)[https://xxhash.com] as used in
(Python's tuple)[https://github.com/python/cpython/blob/849a80ec412c36bbca5d400a7db5645b8cf54f1f/Objects/tupleobject.c#L305]:

we start with a constant `hash_prime1`
for each value:
we take its hash code * `hash_prime2` and add it
then we rotate by `hash_rotate`
and multiply by `hash_prime3`
(T 
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

(a tuple.this.type, b tuple.this.type)
 => 
bool
A total order between two tuples `a` and `b` is defined by the total order of
their first elements. If the first `i` element pairs are equal, the order is defined by
the `i+1`th element pair.

This will result in a runtime `panic` in case any element type is not orderable.
 => 
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`.

Applicable universe features

These are features in universe, that have an argument with a type constraint that matches this features type and can therefore be used with it.
(T 
type
:
property.equatable, a T, b T)
 => 
bool
equals -- feature that compares two values using the equality relation
defined in their type
(T 
type
:
property.hashable, a T)
 => 
u64
hash of a value
(T 
type
:
property.equatable, a T, b T)
 => 
bool
infix = -- infix operation as short-hand for 'equals'
(T 
type
:
property.orderable, a T, b T)
 => 
bool
does this come strictly before other?
infix <= -- infix operation as short-hand for 'lteq'
(T 
type
:
property.orderable, a T, b T)
 => 
order
three-way comparison between this and other.

result is < 0 if this < other
result is > 0 if this > other
result is = 0 if this = other
(T 
type
:
property.equatable, a T, b T)
 => 
bool
infix = -- infix operation as short-hand for 'equals'
(T 
type
:
property.orderable, a T, b T)
 => 
bool
does this come strictly after other?
(T 
type
:
property.orderable, a T, b T)
 => 
bool
does this come after other?
is `a` contained in `Set` `s`?

This should usually be called using type inference as in

is `a` not contained in `Set` `s`?

This should usually be called using type inference as in

(T 
type
:
property.equatable, a T, b T)
 => 
bool
infix ≟ -- infix operation as short-hand for 'equals'
infix ≤ -- infix operation as short-hand for 'lteq'
(T 
type
:
property.orderable, a T, b T)
 => 
bool
does this come after other?
(T 
type
:
property.orderable, a T, b T)
 => 
order
three-way comparison between this and other.

result is < 0 if this < other
result is > 0 if this > other
result is = 0 if this = other
(T 
type
:
property.orderable, a T, b T)
 => 
bool
does this come strictly before other?
(T 
type
:
property.orderable, a T, b T)
 => 
bool
does this come strictly after other?
(T 
type
:
property.partially_orderable, a T, b T)
 => 
bool
lteq -- feature that compares two values using the lteq relation
defined in their type
(T 
type
:
property.orderable, a T, b T)
 => 
T
maximum of two values
memoize `f`.
wraps f so that f will only be called once for every unique input.

The term "memoization" was coined by Donald Michie in 1968 and
is derived from the Latin word "memorandum" ("to be remembered"),
usually truncated as "memo" in American English, and thus carries
the meaning of "turning a function into something to be remembered".
https://en.wikipedia.org/wiki/Memoization

example:

(T 
type
:
property.orderable, a T, b T)
 => 
T
minimum of two values
0.095dev (2025-09-09 14:29:31 GIT hash 98644f8f651c2101a0730cfe31c5807993b7603b built by fridi@fzen)