conversions.md

layout	title	category	tags	order
developer-doc	Defining Functions	syntax	syntax functions	10

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).