Lesson 47(!): xpqz.github.io/cultivations/AtopOver.html

17 to go...

@xpqz Nice chapter, thanks! Is beside also going to be treated in this chapter?

@Richard xpqz.github.io/cultivations/Operators.html#jot

@xpqz Looks good, but doesn't it belong under "Primitive operators"? (It was only presented separately because 18.0 wasn't out yet at the time.) Also, I think the "Jot" chapter should be called "Beside/Bind", as all the other chapters go by primitive name, not glyph name.

@user15236625 Hi Lilith Lovelace. If you want to participate here, please email access@apl.chat

Adám you're near the Dyalog office, right? I'm moving into the "Dyalog Towers" :) it'd be nice to meet you, before you head off to denmark

@FawnLocke I'm leaving London Tuesday mid-day.

Ah, unfortunate

Well, for me at least. I'm sure you're looking forward to it :)

Don't worry, we'll meet. Non-Bramley people visit Bramley (and then stay at the Towers) quite often, and we'll probably meet at some live events too.

Oh, yes. I'm sure. I look forward to it

How can I get this to work, without creating before the variable (I've just found this solution, but I can't use it)

      {a←1 ⋄ {a+⍵} ⍵}2
3
      g ← {a+⍵}
     {a←1 ⋄ g ⍵}2
VALUE ERROR: Undefined name: a
g[0] g←{a+⍵}
        ∧
      a←0
      {a←1 ⋄ g ⍵}2
2

@MasterQuiz Wait, this isn't still working like I want, it's using the global variable. I could passed it as a variable but I wonder if it can be done in a simpler way

as much as it pains me to say this, this is what tradfns do I think

      g←{a+⍵}
      ∇f x;a
       a←1
       g x
       ∇
      f 2
3
      a
VALUE ERROR: Undefined name: a
      a
      ∧

so if you really want dynamic scoping... there you go

@rak1507 I was actually trying to transform a tradfn into a dfn

ah

well you won't get dynamic scoping with dfns

@dzaima So the only thing remained is to pass it to the function as an argument?

or do some horrible namespace thing

or just move the g assignment to within the function

Not recommended method to force dynamic scoping upon dfns:

      g ← {a+⍵}
      ∇z←{x}(F _)y
       :if 900⌶0
           z←F y
       :else
           x←x F y
       :endif
      ∇
      {a←1 ⋄ g _ ⍵}2
3

Also not recommended:

      g ← {a+⍵}
      {a←1 ⋄ ⍎'g ⍵'}2
3

The proper thing to do is pass in as argument or operand.

@Adám So remove a tradfn creating another tradfn?

@Adám Yes, I'm trying this

@MasterQuiz Well, the idea is that you have a single helper tradop, enabling you to code using dfn syntax but with dynamic scoping.

@Adám Do you know that TryAPL convert Power into this thing 'þ'? When I save a function and display it

@MasterQuiz Yes, it is intentional, to protect the server.

@Adám What can it do?

Power can put the system into an uninterruptible loop, and some inverses can crash the interpreter.

Doesn't it stop the execution after 10s?

(The whole stack is open source, so you can have a look how it works.) There's a background thread that terminates long-running user-task threads, but the assassin thread never gets a time slice if ⍣ is running a tight loop.