Do pure functions solve the "return const" problems?

[Janice Caron]

On 02/04/2008, Yigal Chripun <yigal100 at gmail.com> wrote:
>  1) since the purpose of pure functions as I understand it is thread-safe
>  functions,

It isn't. A pure function is a function with no side effects.

> than why should we care if they have side affects

See above. Knowing that a function f is pure allows the compiler to
make optimisations it cannot make with non-pure functions. For
example:

    x = f() + f();

can be optimised to

   x = 2 * f();

thereby eliminating one entire function call. This makes your code go faster.

Pure functions also happen to be thread-safe, but not all thread-safe
functions are pure.