I think Elias is correct.
>From the IBM manual, pg. 110 (check the source; I think I've transcribed
accurately, but make no guarantee):
-- begin
Empty Argument: If R is empty, the function LO is not applied. Instead,
a related function called the fill function of LO is applied with
argument ↑R (the prototype of R). This result is used as a prototype of
the empty array of ρR .
The identity is:
LO¨ ̈R ←→ (ρR)ρ⊂fill fn ↑R
where:
LO Is any function for which a fill function is defined
fill fn Is its related fill function
-- end
That'd mean:
+¨⍬ ←→ ⍬
,¨'' ←→ ''
Also, in the case where a function is a defined function, its fill
function is the identity function. Therefore {⍵}¨'' and {⍵}¨⍬ should
behave according to these identities:
(⍴'')⍴⊂{⍵}↑''
┌⊖┐
│ │
└─┘
(⍴⍬)⍴⊂{⍵}↑⍬
┌⊖┐
│0│
└─┘
On Thu, 2014-05-15 at 00:14 +0800, Elias Mårtenson wrote:
I tested this, and I'm wondering if the return value should really be
0? Wouldn't it make more sense to return ⍬?
Regards,
Elias