Re: [Bug-apl] Local sysvars in lambdas

[Juergen Sauermann]

Hi Louis,

so I suppose this was not an issue.

BTW if you believe a lambda behaves differently than a defined function then
you can check the lambda with *⎕CR*, e.g.:

*ADD←{⍺+⍵;C;⎕IO;D}**
**      ⎕CR 'ADD'**
**λ←⍺ λ1 ⍵;C;⎕IO;D*
*λ←⍺+⍵ *

Or, in your example:

*      f←{⍎(⍵>1)⊃'⍵' '⍵×⍙ ⍵-1'⊣⎕IO←0;⎕IO}**
**      ⎕CR 'f'**
**λ←λ1 ⍵;⎕IO **
**λ←⍎(⍵>1)⊃'⍵' '⍵×⍙ ⍵-1'⊣⎕IO←0*

In GNU APL a lambda is turned into a normal defined functions right 
after its body was parsed.

/// Jürgen


On 08/25/2016 03:15 PM, Louis de Forcrand wrote:
> Yep, still 0 after )SIC.
> I checked it with this function:
>
>       ∇F;⎕IO
> [1] ⎕IO←~⎕IO ◊ →1∇
>
> And indeed ⎕IO goes back to its original value after )SIC.
>
> Thank you. I should have put that in the original email.
>
> Louis
>
> > On 25 Aug 2016, at 04:01, Christian Robert 
> > <address@hidden <mailto:address@hidden>> wrote:
> >
> > After second though, you may have/had a point.
> >
> > keep investigating.
> >
> > Xtian.
> >
> > On 2016-08-24 21:54, Louis de Forcrand wrote:
> > > You are entirely right, I didn't do that when I reproduced it for 
> > > the email. However I believe that I did check quad IO after )SIC the 
> > > first time it happened and it was still 0.
> > > Almost like the variables being localised are localised after execution?
> > > I'll check again when I can.
> > >
> > > Thanks for pointing that out.
> > > Louis
> > >
> > > > On 25 Aug 2016, at 03:39, Christian Robert 
> > > > <address@hidden <mailto:address@hidden>> 
> > > > wrote:
> > > >
> > > > try ⎕IO
> > > >
> > > > *after*  )sic
> > > >
> > > > the fact is that when a function is interruped, you see "by the 
> > > > last" interrupted function. Until you type )sic or )reset
> > > >
> > > > my 2 cents, as usual, I may be wrong.
> > > >
> > > > Xtian.
> > > >
> > > >
> > > > > On 2016-08-24 21:09, Louis de Forcrand wrote:
> > > > >    ∇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