Assignability, variance and type compatibility
Comes up in: Coding
This concept is being written. It gets the full five steps — explanation, predict, interview angle, practice with tests, and review cards. Here is exactly what it will cover, so you can study it elsewhere in the meantime.
What it covers
- subtypes
- covariance and contravariance (function parameters with
strictFunctionTypes - method bivariance)
in/outvariance annotations- why arrays are covariant (unsound)
Words you will know
What you will practise
- predict 8 assignability results
Interview questions this answers
- Explain covariance and contravariance with function parameters.