Function (computer programming): Difference between revisions

Revision as of 23:11, 13 May 2025

Revision as of 04:31, 31 May 2025

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==== Compiler optimization ====

Some optimizations for minimizing call overhead may seem straight forward, but cannot be used if the callable has side effects. For example, in the expression <code>(f(x)-1)/(f(x)+1)</code>, the function <code>f</code> cannot be called only once with its value used two times since the two calls may return different results. Moreover, in the few languages which define the order of evaluation of the division operator's operands, the value of <code>x</code> must be fetched again before the second call, since the first call may have changed it. Determining whether a callable has a side effect is difficult {{endash}} indeed, [[undecidable problem|undecidable]] by virtue of [[Rice's theorem]]. So, while this optimization is safe in a purely functional programming language, a compiler for ana language not limited to functional typically assumes the worst case, that every callable may have side effects.

==== Inlining ====