> all mainstream languages have eager evaluation models That is incorrect, e.g. Java Streams (Javas built in library for functional processing of data) are laz

> all mainstream languages have eager evaluation models That is incorrect, e.g. Java Streams (Javas built in library for functional processing of data) are lazy, which can surprise beginners. You say it's just an std lib and not a lazy programming language? Ok, the much older (but just as lazy) C# linq is directly integrated in the C# language, making the C# language both eager and lazy by default, depending on which parts you use.