Before java and c++ introduced lambada, I thought delegate is the foundation of lambdas.
Now I think lambda is an industry standard, implemented differently in c++ and java. See post on “lambda – replicable”. For python…
Bear in mind
A) the most fundamental, and pure definition of lambda — a function as rvalue, to be passed in as argument to other functions.
B1) the most common usage is sequence processing in c#, java and c++
* c# introduced lambda along with linq
* java introduced lambda along with streams
B2) 2nd common usage is event handler including GUI.
See post on “2 fundamental categories”