[bunderbunder]

All valid points.

If you're going to do this sort of thing with much success, you really need to have a language with a fairly powerful type system. If function pointers are your only option for higher-order programming, I wouldn't even try. First class functions or interface polymorphism help, but I'd also want to have a language that makes it relatively easy to create (and enforce) types so that your extension points don't end up being overly generic.

[thaumasiotes]

What distinction are you drawing between "first-class functions" and "function pointers"?

[bunderbunder]

About the same distinction as I'd draw between an integer and a pointer to an integer.

[kazinator]

Both function pointers and "first class functions" refer to function indirection.

In its treatment of expressions, C doesn't draw the distinction between function and pointer to function. When you call printf("foo\n"), the printf part is a primary expression which designates a function, and evaluates to a function pointer. That pointer is then dereferenced by the postfix ().

The main difference between a "first class" function and a function pointer is that a first class function carries an environment, which allows the body of the function to make references to lexically scoped names outside of the function. A function pointer carries a reference to the code only.

[moogleii]

>The main difference between a "first class" function and a function pointer is that a first class function carries an environment

Isn't that specifically a closure? I think first class functions have a more general definition.