digitalmars.D - Does D support tail recursion?
Jerry <Jerry_member pathlink.com> writes:
Hi, In some ML languages like Ocaml the compiler detects tail-recursions and automatically changes it to a while loop before assembling into machine code. Does D have this tail-recursion-optimization too? -Jerry
Aug 08 2005
Burton Radons <burton-radons smocky.com> writes:
Jerry wrote:In some ML languages like Ocaml the compiler detects tail-recursions and automatically changes it to a while loop before assembling into machine code. Does D have this tail-recursion-optimization too?
No and yes. Tail recursion has two meanings: as a language-mandated optimisation to ensure that a valid tail recursion pattern doesn't result in a stack overflow, and as a simple optimisation pattern that a compiler might recognise. D has the latter meaning: a compiler can apply the optimisation but it's not required to. In a test, DMD does a tail recursion when -O is used, but not without. It didn't do tail recursion if an auto class is used as a local, so it wouldn't do it in the case of any try/finally block either and I don't know what complexity limit there is before it'll abandon the optimisation. It really needs a tail recursion keyword to ensure that if the compiler can't tail-recurse it, then the code is considered erroneous.
Aug 08 2005
Stewart Gordon <smjg_1998 yahoo.com> writes:
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Aug 10 2005