anonymous function parsing bug?

Hi,

thx for the reply. Unfortunately that is not a simplified version of the 
problem. You have a function, call it and get the result (numeric in, 
numeric out in that case). For simplicity lets use the "return" case:

##
foobar<-function(x) { return(sqrt(x)) }(2)
##
which is a function (numeric in, numeric out) which is defined, then 
gets called and the return value is a function (with an appendix of 
"(2)" which gets ignored), not the numeric.

In my opinion the result of the expression above should be a numeric 
(1.41... in this case) or an parser error because of ambiguities.

e.g. in comparison with node.js

##
function(x){
     return(2*x)
}(2);
##

leads to

##
SyntaxError: Unexpected token (
##

Or Haskell (and basically every complete functional languange)
##
(\x -> 2*x) 2
##
which leads to 4 (... okay, that is not comparable because here the 
parenthesis make a closure which also works in R or node.js).

However, I think it's weird that

 > ( function(x) { return(2*x) } ( 2 ) ) (3)

is a legal statement which results to 6 and that the "(2)" is basically 
ignored by the parser.

Furthermore it is very strange, that

##
f1<-function(x) { print(2*x) }(2)
f1(3)
##
does the command and gives an error ("attempt to apply non-function") and
##
f2<-function(x) { return(2*x) }(2)
f2(3)
##
is perfectly fine. Thus the return statement changes the interpretation 
as a function? Or do I miss something?

Best wishes

Wilm

Am 21.10.2016 um 17:00 schrieb William Dunlap:

anonymous function parsing bug?

Thread (10 messages)