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Implementation of **type checks** for **intersection types**. The idea is to split the list of `types[]` in `EnsoMultiValue` into two parts: - first `methodDispatchTypes` represent the types the value _"has been cast to"_ - the rest of the types represent the types the value _"can be cast to"_ By performing this separation we address the #10882 requirements. After a type check only methods available on the `methodDispatchTypes` can be invoked. However the value can still be cast to all the possible types.
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| layout | title | category | tags | order | ||
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| developer-doc | Defining Functions | syntax |
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Conversions
Conversions are special functions associated with a type,
named from and taking single that argument. Following example:
type Complex
Num re:Float im:Float
Complex.from (that:Float) = Complex.Num that 0
defines type Complex and a conversion from Float which uses the provided Float value as
real part of a complex number while setting the imaginary part to zero.
Type Checks
Conversions are integral part of type checking during runtime. Having the right conversion in scope one can write:
complex_pi = 3.14:Complex
to create a new instance of type Complex. The Enso runtime represents
the 3.14 literal as Float value and that would fail the Complex type check if there was no
conversion method available. However as there is one, the runtime uses Complex.from behind the
scene and complex_pi then becomes Complex.Num 3.14 0 value.
Type checks may perform no, one or multiple conversions (like in case of intersection types).