On 09/29/2017 12:41 PM, Brandon Allbery wrote:
On Fri, Sep 29, 2017 at 3:27 PM, ToddAndMargo <toddandma...@zoho.com
<mailto:toddandma...@zoho.com>> wrote:
I do not understand. :'(
There's not enough syntax to go around, so perl 6 has to use spaces
sometimes to figure out what you want.
$ perl6 -e 'my $x="abc"; $x[R~]= "yyz"; say $x;'
===SORRY!=== Error while compiling -e
Missing required term after infix
I explained this one earlier. Things would go faster if you read entire
messages.
The sequece `$x[` could potentially mean that $x is an array stored in a
scalar variable, and you are asking for a particular item from the
array. Or it could mean the start of a complex operator to be applied to
$x. You need a space to tell it which you intend: without the space it
sees the indexing operation, without it sees the complex operator.
Ding! It finally sunk in. "$x[" is an index, where "$x [" means an
operation. Took a bit, but I finally got there.
In this case, the complex operator is composed of a basic operator '~'
(string concatenation), modified twice: once with the reversing
metaoperator (Rop), and a second time with the in-place assigment
operator (postfix =). Just as you need to use parentheses in `2 + 3 * 5`
if you want it to be (2 + 3) * 5 instead of 2 + (3 * 5), you need braces
to tell it how to combine these special operators --- and you must *not*
have a space before the postfix =. Which is why you got this error:
$ perl6 -e 'my $x="abc"; $x [R~] = "yyz"; say $x;'
===SORRY!=== Error while compiling -e
Preceding context expects a term, but found infix = instead
With the space before it, it is no longer a modifier for the reversed
concatenation [R~] but a standalone assignment operator, which can't
happen there because it already has an operator [R~] so now it needs to
see a term (expression, roughly).
Hi Brandon,
Some of my issues comes from Modula2 where stings and arrays of
characters. And perl 5 with is "~=" or "=~". I forget.
Thank you for your patience!
-T
