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switch

switch

§
(A 
type
, B 
type
)
:
choice A, B,monad A, switch.this A B  
[Contains abstract features]
switch is the parent feature of all choices
that encode success and failure,
e.g. option (something/nil)
or outcome (something/error)
הההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההה
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Type Parameters

Functions

returns o if outcome is ok, otherwise return the outcome's own
error.
synonym for infix >>=
this switch as an equatable_switch
converts switch into a list of either a single element in case
switch.this.exists or `nil`otherwise
convert this switch to an option
convert this switch to an outcome
convert this switch to an outcome
§
 => 
String  
[Redefinition of  Any.as_string]
converts switch to a string

redefines:

§
 => 
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.
Does this switch contain a value of type A?
§
 => 
switch.A
unwraps a switch that is known to contain a value

this can only be called in cases where it is known for sure that this switch
is not nil. A runtime error will be created otherwise.
§
(default Lazy switch.A)
 => 
switch.A
unwrap value or get default
monadic operator

redefines:

§
(B 
type
, MB 
type
:monad (monad.infix >>=~.B) (monad.infix >>=~.MB), f Unary MB monad.A)
 => 
MB  
[Inherited from  monad]
  
[Abstract feature]
monadic operator to another monad

Apply f to elements of type A and wrap them in MB.
§
(MMA 
type
:monad monad.MA monad.join.MMA, a MMA)
 => 
monad.MA  
[Inherited from  monad]
  
[Abstract feature]
join operator
Does this switch contain a value of type A?
if this switch is nil return the result of f
otherwise just return this switch.
§
(default Lazy switch.A)
 => 
switch.A
unwraps an switch if it exists, returns default value otherwise.
short-hand postfix operator for '!exists'
short-hand postfix operator for 'exists'
short-hand prefix operator for '!exists'
§
 => 
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.
§
 => 
switch.A
value of a switch that is known to contain a value

This can only be called in cases where it is known for sure that this
switch is not a B. A runtime error will be created otherwise.
§
(default switch.A)
 => 
switch.A
value of a switch or default if switch contains B

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
)
 => 
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.

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
same
pre T : property.equatable
הההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההה
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=>
a = b
הההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההה
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or

val(n T) is

# check if T is numeric, if so
# return true if n > zero,
# return nil if T is not numeric
#
more_than_zero option bool =>
if T : numeric then
n > T.zero
else
nil
הההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההה
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§
 => 
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:

§
(a monad.type.A)
 => 
monad.type.MA  
[Inherited from  monad]
  
[Abstract feature]
return function
§
(a choice.this.type (in type feature))
 => 
choice.this.type (in type feature)  
[Inherited from  choice]
explicitly tag value a to become choice
§
 => 
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`.
0.093dev (2025-05-13 15:50:27 GIT hash 38f965e14265a6f3ba3f96f18ddedb79352428af built by fridi@fzen)