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Comment by chx | Hacker News Reader

PHP implements closures as objects and I wrote a blogpost which shows the equivalence at http://drupal4hu.com/node/339.html .

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C++ too - a lambda expression (with optional captures) is literally defined in terms of transforming the expression into an instance of a local unnamed class. And of course Java where the equivalence is supremely explicit - before Java 8 anonymous inner classes were the way to implement closures, and the Java 8 lambda expressions are merely syntactic sugar for creating an equivalent AIC instance.

> Java 8 lambda expressions are merely syntactic sugar for creating an equivalent AIC instance

I think that's a decent way to explain java's lambda expressions to developers without fp experience, but it's not technically correct. Lambda expressions are compiled into static methods in the class file.

/pedantic

Hah, I never thought of it that way. In Lisp, you use lambdas to define classes. In C++, you use classes to define lambdas.

Ah this reminds me of all the different proposals for closure syntax in Java before it was implemented, the following links put compare some of the proposals:

1. http://www.artima.com/weblogs/viewpost.jsp?thread=180638 (Inner Classes or Closures)

2. http://www.artima.com/weblogs/viewpost.jsp?thread=182412 (Clear, Consistent, and Concise Syntax (C3S) for Java)

3. https://www.artima.com/weblogs/viewpost.jsp?thread=202004 (Comparing Inner Class/Closure Proposals)

PS. I remember the Artima articles because I liked them at the time.

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