Why Tailcalls
From JVMLangSummit
Are tailcalls fated to come in second place on every feature priority list?
Let's gather the use cases and consider the implementation.
(Note: This page is about "hard tail calls" as defined in the Rose blog. Soft TCO is already in many compilers, but does not have a strong effect on software architecture.)
Contents |
use cases
multi-core task distribution
(Doug Lea) chaining task execution; without tail calls you blow the stack needlessly
languages with guaranteed TCO
These are languages with functional patterns, including Scheme, Scala, F#. Seph also aims to give this guarantee.
guaranteed disposal of stack-frame
Clojure needs workarounds to avoid floating garbage
public static int count(Object o) {
if (o instanceof Counted)
return ((Counted) o).count();
return countFrom(Util.ret1(o, o = null));
}
static public Object ret1(Object ret, Object nil) { return ret; }
Reduce call stack size !
(Rémi) Avoid to show language implementation internals by collapsing runtime stack frame.
Kōan
Tail call... Booty call... More than a coincidence? You decide.
