[Bug-apl] Local sysvars in lambdas

[Louis de Forcrand]

      ∇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