Clarify function types in `Anonymous Function` section in `Functions` documentation

Hi @chetandr-lohono! "Closure" has a wide definition in common use. It includes function values in general, function values which actually close over variables in their scope, and anonymous function expressions/function literals (which create function values).

I think you're correct that lambda and anonymous function are much closer to being synonymous. But, I don't think closure is so unrelated that it needs to be removed from the anonymous functions section. A closure is a something like a more specific case of anonymous functions, or a case that makes use of anonymous functions, so can be considered a form of an anonymous function.

So where it says "...You can also create a nameless function called an anonymous function, or sometimes a lambda or closure." is not inaccurate because closures are "nameless" functions. For the intents of teaching Dart, it's safe enough to use the common understanding and group "closure" with "anonymous function". (If you want a closure example in Dart, the Isolates page has a simple one).

A similar question on stack overflow was answered by one of Dart's engineers, and provides helpful context.

The respective sections on each term's Wikipedia page are also helpful for understanding the academic definitions of how the terms overlap:

Anonymous function page's section on Closures
Closures page's section on Anonymous functions

It also might be helpful to note that some other languages (like Swift and Rust) call their implementations of anonymous functions closures.

Does that help? Please let us know!

dart-lang / site-www

Clarify function types in `Anonymous Function` section in `Functions` documentation #5535

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