Re: [Bug-apl] dynamic function not referencing global?

[Juergen Sauermann]

Hi,

correct. To explain why this is so, consider this:

      {1+2}
3

      {1+⍵}
SYNTAX ERROR

      {1+⍵} 5
6

Therefore in

      F0←{1+2}

GNU APL first reduces {1+2} to 3 and then assigns 3 to F0, making F0 a variable
because a values is being assigned to a name. This is normal APL and holds for
all niladic functions and not only for niladic lambdas.

In contrast, in

      F1←{1+⍵}

{1+⍵} cannot be reduced (as opposed to {1+⍵} 5 which can), so it is shifted onto
the evaluation stack, then ← is shifted (still not being able to be reduced), and finally
 F1 is shifted. At this point the stack contains the valid phrase F1←{1+⍵}, which can
be reduced and causes F1 to become a monadic function bound to the name F1.

/// Jürgen

On 10/25/2016 07:01 PM, Christian Robert wrote:

DISPLAYhand←{,(⍪hand),' '}

this create a variable DISPLAYhand

this is because de {} does not contain neither alpha nor omega.

Xtian.


On 2016-10-25 12:54, address@hidden wrote:

Hi bug-apl,

Why does DISPLAYhand not use the new value of hand on the second call?


      deck←''
      deck←deck,"🂢" "🂲" "🃂" "🃒"
      deck←deck,"🂣" "🂳" "🃃" "🃓"
      deck←deck,"🂤" "🂴" "🃄" "🃔"
      deck←deck,"🂥" "🂵" "🃅" "🃕"
      deck←deck,"🂦" "🂶" "🃆" "🃖"
      deck←deck,"🂧" "🂷" "🃇" "🃗"
      deck←deck,"🂨" "🂸" "🃈" "🃘"
      deck←deck,"🂩" "🂹" "🃉" "🃙"
      deck←deck,"🂪" "🂺" "🃊" "🃚"
      deck←deck,"🂫" "🂻" "🃋" "🃛"
      ⍝deck←deck,"🂬" "🂼" "🃌" "🃜"   ⍝knights
      deck←deck,"🂭" "🂽" "🃍" "🃝"
      deck←deck,"🂮" "🂾" "🃎" "🃞"
      deck←deck,"🂡" "🂱" "🃁" "🃑"
      deck ← ⊖13 4 ⍴ deck

      hand←(∈deck)[13?52]
      DISPLAYhand←{,(⍪hand),' '}

      DISPLAYhand
🂢 🃈 🃃 🂷 🃞 🃙 🃝 🂫 🃋 🃕 🃒 🃂 🂧
      hand←(∈deck)[13?52]
      DISPLAYhand
🂢 🃈 🃃 🂷 🃞 🃙 🃝 🂫 🃋 🃕 🃒 🃂 🂧
      hand
🂤🂺🂾🂷🂪🂱🂳🂸🃚🃅🂻🂲🂭


Thanks,
Alex