From: daniel@...42.com
Date: 2019-09-04T14:54:09+00:00
Subject: [ruby-core:94778] [Ruby master Feature#12543] explicit tail call syntax: foo() then return

Issue #12543 has been updated by Dan0042 (Daniel DeLorme).


Questions:
1. Is it possible to use "partial" tail-call optimization, where the backtrace is kept but all other frame state is discarded?
2. Is it possible to detect tail-recursion and turn on optimization just for that?

----------------------------------------
Feature #12543: explicit tail call syntax: foo() then return
https://bugs.ruby-lang.org/issues/12543#change-81396

* Author: mame (Yusuke Endoh)
* Status: Assigned
* Priority: Normal
* Assignee: matz (Yukihiro Matsumoto)
* Target version: 
----------------------------------------
How about introducing a new syntax for tail call?

```
def foo()
  foo()
end
foo() #=> stack level too deep
```

```
def bar()
  bar() then return
end
bar() #=> infinite loop
```

* no new keyword (cf. `goto foo()`)
* no conflict with any existing syntax
* an experimental patch is available (attached)
* no shift/reduce nor reduce/reduce conflict in parse.y

-- 
Yusuke Endoh <mame@ruby-lang.org>

---Files--------------------------------
then_return.patch (9.18 KB)


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