Maximally minimal stack trace standardization

Sam Tobin-Hochstadt samth at
Tue Sep 30 07:31:35 PDT 2014

On Tue, Sep 30, 2014 at 6:56 AM, Andreas Rossberg <rossberg at> wrote:
> On 29 September 2014 19:25, Brendan Eich <brendan at> wrote:
>> Mark S. Miller wrote:
>>> That's why, IIRC (haven't checked lately), TCO is only specified for calls
>>> from non-sloppy functions.
>> PTC (Proper Tail Calls), not TCO. It's confusing to equate the two, from
>> what I know (corrections welcome0.
> Hm, people most often refer to "mandatory tail call
> optimisation/elimination" when talking about a spec level requirement.
> I have never seen "PTC" used in a formal context, let alone the
> acronym.

Clinger's paper, which formalizes the concept, calls it "proper tail
recursion" in the title, as does the R5RS Scheme standard. Since
recursion isn't fundamental, though, proper tail calls seems more
accurate. This terminology is used lots of places these days, such as
the Lua docs and this (archive of a) post by Guy Steele:


More information about the es-discuss mailing list