[ruby-core:94710] [Ruby master Feature#12543] explicit tail call syntax: foo() then return

Issue #12543 has been updated by ko1 (Koichi Sasada).

Status changed from Closed to Assigned

Another idea: `tailcall return foo()`

* Background: `return` is void expression and any `method(return)` is not prohibited on current compiler. So nobody use it == no-incompatibility. Any keywords are acceptable (example: `goto return foo()`).

----

I like Endoh-san's original idea, tailcall explicitly. It is similar to goto, and programmer should understand there is no backtrace.

I heard that someone want to use taicall with pattern matching which will be introduced into Ruby 2.7.


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Feature #12543: explicit tail call syntax: foo() then return
https://bugs.ruby-lang.org/issues/12543#change-81320

* 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 <[e-mail]>

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


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