ERROR: syntax: extra token ".." after end of expression

[pygy]

julia> ..(a,b) = b - a
.. (generic function with 1 method)

julia> 4 .. 6
2

julia> 4 .. 6 .. 7
ERROR: syntax: extra token ".." after end of expression

Maybe linked to the #2614 fix?

[JeffBezanson]

I'm not sure what the precedence or associativity of .. should be. If it's like ., it should have very high precedence.

[mschauer]

People liked this operator in the past as variant of . which would imply high precedence or as some kind of range constructor : which would imply low precedence, hard to call.

[pygy]

FWIW it is really about more than one .. operator in a single expression:

julia> ..(a, b) = a * b
.. (generic function with 1 method)

julia> "a"*"b".."c"
"abc"

julia> "a".."b"*"c"
"abc"

julia> "a".."b"*"c".."d"
ERROR: syntax: extra token ".." after end of expression.

[brenhinkeller]

So this one is still true in 1.8.3

julia> ..(a,b) = b - a
.. (generic function with 1 method)

julia> 4 .. 6
2

julia> 4 .. 6 .. 7

ERROR: syntax: extra token ".." after end of expression
Stacktrace:
 [1] top-level scope
   @ none:1

[mschauer]

The consequence of being forced to be explicit (4 .. 6) .. 7 or 4 .. (6 .. 7) seems benign, one less associativity to be remembered.

[brenhinkeller]

Yeah, fair. It certainly doesn't seem to have been causing much trouble in the intervening years. I'll close as not planned then, but if folks disagree they should feel free to undo.