Decodal/doc/manual/source/language/expression/function-call.md

Function Call Expression

A function call expression applies a function value to arguments.

increment(41)

Evaluation

An argument is evaluated when the function body references it. If the argument is referenced several times, its evaluation result is reused. When a parameter has a range, the argument is refined using the same rules as narrower as wider. Fields present only in the parameter range remain abstract, and defaults are not selected at this point.