∇Z←F N;⎕IO
[1] Z←⍎(N>1)⊃'N' 'N×F N-1'⊣⎕IO←0∇
F 6
720
f←{⍎(⍵>1)⊃'⍵' '⍵×f ⍵-1'⊣⎕IO←0;⎕IO}
f 6
SYNTAX ERROR
λ1[1] λ←⍎(⍵>1)⊃'⍵' '⍵×f ⍵-1'⊣⎕IO←0;⎕IO
^ ^
⎕IO
0
)SIC
⎕IO←1
f←{⍎(⍵>1)⊃'⍵' '⍵×⍙ ⍵-1'⊣⎕IO←0;⎕IO}
f 6
VALUE ERROR
⍵×⍙ ⍵-1
^
⎕IO
0
)SIC
As is shown, system variables such as ⎕IO cannot be localised
in lambdas as they can be in del-fns.
The last example is there because I just thought the order of
execution was intriguing: it seems to show that the error with
local ⎕IO was signalled at the end (left) of the lambda. This
of course might be as it should.
In addition I was wondering if there is a way to refer to the
enclosing lambda / function anonymously, i.e. ∇ in Dyalog.
That is how I first entered the faulty symbol, and found this
potential bug.
Good luck,
Louis
