The CAGE Prohibits Storing Objects Formed Differently

• @maxonfjvipon
• 04 Aug 2023
• comments

In the recently released version 0.30.0 we’ve changed the writing mechanism of cage object. Until now, we could store and write to cage any object we wanted. But cage became smarter and stricter and can store only objects that have the same “form” now.

A few words about “form” and “formation.” Let’s take a look at the code below:

[name] > cat
  [] > voice
    stdout
      sprintf
        "Meow from %s"
        name

This is a “formation” of the object cat. Here we can say that the “form” of object cat is “cat.”

cat "Lisa" > lisa

Here object cat was copied and its free attribute name was set to “Lisa.” Now we can say that object lisa “was formed by” object cat and has the same “form”—”cat.”

Let’s get back to the object cage. The object is used as temporary storage of objects in memory. It should be remembered that cage does not dataize a stored object.

Here is the typical example how cage was used before:

cage 0 > cg

seq > @
  cg.write lisa

Here we copy object cage and store the object 0 (which is “formed by” object int) in it, and then we write an object lisa to it.

Such behavior is prohibited now and will lead to exception throwing. Object cage can store inside only objects of the same “form.”

The next code will work since object cat and lisa have the same “form”–”cat”:

cage cat > cg

seq > @
  cg.write lisa

You may wonder why we did it. Here it’s time to talk a bit about our plans for EO.

We believe that EO can be used as intermediate representation for performing optimizations for many object-oriented programming languages. To achieve that, we have to make EO stronger and stricter. This is how we’re about to do it:

• Prohibit writing objects formed differently into cage (done)
• Prohibit writing objects formed differently into memory
• Prohibit weak atoms typing ([] > atom /?)

Be in touch and see you soon.