On Rehacktoring

Posted in programming on May 6th, 2014 by Samuel Kenyon

For at a least a year now, I’ve been using the term “rehacktor,” a portmanteau of “refactor” and “hack.” Although I came up with it on my own, I was not surprised that googling it resulted in many hits. Perhaps we are witnessing the convergent evolution of an urgently needed word.

My definition was at first a tongue-in-check descriptor in VCS commits for refactoring tasks that I was not pleased about. However, upon reflection, I think the term and the situation which leads to its necessity is important.

But first, how are others using this term?

Other Definitions

One “intertubeloper” (a term I just coined) tweeting as WizOne Solutions has tried to establish this unsatisfactory definition:

Rehacktoring (n.) – The act of reaching a level of hackedness so great that the resultant code is elegant and sophisticated.

Something a bit more sensible is the concept of rehacktoring as refactoring without tests (for instance a Twitter search of “rehacktoring” will get some results along those lines).

My one minute research bout also found a recent blog post by Katrina Owen which contains the string “Refactoring is Not Rehacktoring.” Her article paradoxically offers a meaning by not defining “rehacktoring.” She explains via some strategies how one way to refactor is to change in baby steps. Each step results in code that still passes the tests. Each intermediate step may be ugly and redundant, but the tests will still pass—if they don’t you revert and retry.

I’ve been using this baby-step refactoring strategy for a long time, having come up with it on my own. But as I read Owen’s post I realized that if one does not follow through with the full refactoring, one might end up with a ridiculous state of the code which is not necessarily any better than its pre-refactoring state. In that sense, “rehacktoring” can be a retroactive term to describe an abandoned refactoring.

Owen meant for “rehacktoring” to mean unsafe code changes (I think). Both that meaning and abandoned refactoring should be valid variations.


Aside from those notions, I propose another valid meaning: any refactoring effort which is a mini death march. In other words, the refactoring has a high chance of failure due to schedule, resources, etc. I would guess a common trigger of rehacktoring are managers demanding refactoring of crappy code that is critical to a deployed application.

But refactoring is not the only answer. There are other options, regardless of what John Manager or Joe Principal claims. Some very legitimate alternatives include, but are not limited to:

  • Don’t refactor. Spend time on other/new functionality.
  • Rewrite the class/module/application from scratch.
  • Stretch the refactoring out to a longer time frame, so that everyone involved is still spending most of their effort on new functionality that users care about.

The proposal to rewrite a module or application from scratch will scare those of weaker constitution. But it does work in many circumstances. Keep in mind that the first crack at doing something new might be the necessary learning phase to do it right the second time. A manager, or your own mind, might convince you that refactoring is quicker and/or lower risk than redoing it. But that is not always the case, especially if you are more motivated to make something new than tinker with something old. And I have seen the rewrite approach work in the wild with two different programmers, in which an intern writes working version 1, and then someone else (even another intern) writes version 2.

Rehacktoring may be the wrong thing to do. It is especially the wrong thing to do if it causes psychological depression in the programmer. After all, who wants to waste their life changing already-working code from bad to semi-bad? Based on observations (albeit not very scientific), I suspect that programmers are particularly ill-suited to refactoring code that they did not originally write. They have no emotional connection to that code. And that makes the alternate solutions listed above all the more appealing for the “soft” aspect of a software team.

Tags: ,

On That Which is Called “Memory”

Posted in artificial intelligence, philosophy on April 19th, 2014 by Samuel Kenyon

Information itself is a foundational concept for cognitive science theories.

But the very definition of information can also cause issues, especially when the term is used to describe the brain “encoding” information from the senses without any regard for types of information and levels of abstraction.

Some philosophers are concerned with information that has meaning (although really everybody should be concerned…) and the nature of “content.” Prof. of Philosophical Psychology Daniel D. Hutto posted an article recently on memory [1]. He points out the entrenched metaphor of memories as items archived in storehouses in our minds and the dangers of not realizing the metaphor.

Hutto also points out two important and different notions of information:

  1. covariant
  2. contentful
rings of a tree carry information about the age of the tree

rings of a tree carry information about the age of the tree

Information as covariance is one of the most basic ways to define information itself philosophically. Naturally occurring information, and presumably artificial information, is at least covariance. I.e., information is the relationship between two arbitrary states which change together always (or at least fairly reliably).

What is content as philosophers use the term? I’ve mentioned the issue with that term before; here we will pretend it means representations. It’s common and easy to describe thoughts as built out of representations of things, be they real or imaginary, since those things are not actually inside a person’s brain, and to the best of our knowledge there is not some ethereal linkage between a real object and a thought of that object (although it makes for exciting fiction to build a world in which any story written by a character creates a new universe where that fantasy is real).

I think content is built off of covariance. And what we often think of as “remembering” and “recall” are abstractions resting on several lower layers.

Behavioral AI

Herbert, a robot by Jonathan Connell, a student of Rod Brooks

Herbert, a robot by Jonathan Connell, a student of Rod Brooks

I think if Rod Brooks [2] and company (Connell, Flynn, Angle and others) had continued their research in certain directions they might have actually achieved layered mental architectures with learning capabilities, either by design and/or emergence. And they would have emergent internal behavior that could be referred to as “memory,” and not like memory in a computer but like memory in an animal.

Memory in a system grown from reflexive subsystems is not just a module dropped in—it is in the nature of the system. And if that unspecific nature makes it difficult to use the term “memory” than so be it. Maybe memory should be abandoned for this kind of project since the word recalls “storage” and a host of computational baggage which is very achievable in computers (indeed, at many levels of abstraction) but misleading for making bio-inspired embodied situated creatures.


Hutto claims that contentful information is not in a mind—it requires connections to external things [1]:

Yet arguably, the contents in question are not recovered from the archives of individual minds rather they are actively constructed as a means of relating and making claims about past happenings. Again, arguably, the ability is not stem purely from our being creatures who have biologically inherited machinery for perceiving and storing informational contents, rather this is a special competence that that comes only through mastery of specific kinds of discursive practices.

As that quote introduces, Hutto furthermore suggests that human narrative abilities, e.g. telling stories, may be part of our developmental program to achieve contentful information. If that’s true then it means my ability to pull up memories is somehow derived from childhood learning of communicating historic and fictional narratives to other humans.

Regardless of whether narrative competence is required, we can certainly explore many ways in which a computational architecture can expand from pre-programmed reflexes to conditioned responses to full-blown human level semantic memories. It could mean there are different kinds of mechanisms scaffolded on top of each other, as well as scaffolded on externally available interactions, and/or scaffolded on new abstractions such as semantic or pre-semantic symbols composed of essentially basic reflexes and conditioning.

What We Really Want from a Robot with Memory

A requirements approach could break down “memory” into what behaviors one wants a robot to be capable of regardless of how it is done.

A first stab at a couple parts of such a decomposition might be:

  1. It must be able to learn, in other words change its internal informational state based on current and previous contexts.
  2. Certain kinds of environmental patterns that are observed should be able to be reproduced to some degree of accuracy by the effectors.

In number 2, I mean remembering and recalling “pieces of information.” For example, the seemingly simple act of Human A remembering a name involves many stages of informational coding and translation. Later the recollection of the name involves a host of various computations in which the contexts trigger patterns at various levels of abstraction, resulting in conscious content as well as motor actions such as marking (or speaking) a series of symbols (e.g. letters of the alphabet) that triggers in Human B a fuzzy cloud of patterns that is close enough to the “same” name. Human B would say that Human A “remembered a name.” Or if the human produced the wrong marks, or no marks at all, we might say that the human “forgot a name” or perhaps “never learned it in the first place.”


  1. Hutto, D. D. (2014) “Remembering without Stored Contents: A Philosophical Reflection on Memory,” forthcoming in Memory in the Twenty-First Century. https://www.academia.edu/6799100/Remembering_without_Stored_Contents_A_Philosophical_Reflection_on_Memory
  2. Brooks, R. A. (1991). Intelligence without representation. Artificial intelligence, 47(1), 139-159.

Image Credits

  1. Nicholas Benner
  2. Cyberneticzoo

Tags: , , ,

Polymorphism in Mental Development

Posted in artificial intelligence on March 9th, 2014 by Samuel Kenyon

Adaptability and uninterrupted continuous operations are important features of mental development.

An organism that can’t adapt enough is too rigid and brittle—and dies. The environment will never be exactly as expected (or exactly the same as any other previous time during evolution). Sure, in broad strokes the environment has to be the same (e.g. gravity), and the process of reproduction has limits, but many details change.

During its lifetime (ontogeny), starting from inception, all through embryogeny and through childhood and into adulthood, an organism always has to be “on call.” At the very least, homeostasis is keeping it alive. I’d say for the most part all other informational control/feedback systems, including the nervous system which in turn includes the brain, all have to be always operational. There are brief gaps, for instance highly altricial animals depend on their parents protecting them as children. And of course there’s the risk when one is asleep. But even in those vulnerable states, organisms do not suddenly change their cognitive architectures or memories in a radically broken way. Otherwise they’d die.

There are a couple computer-ish concepts that might be useful for analyzing and synthesizing these aspects of mental development:

  1. Parameter ranges
  2. Polymorphism

These aren’t the only relevant concepts; I just happen to be thinking about them lately.

Parameter Ranges

Although it seems to be obvious, I want to point out that animals such as humans have bodies and skills that do not require exact environmental matches. For example, almost any human can hammer a nail regardless of the exact size and shape of the hammer, or the nail for that matter.

Crows have affordances with sticks and string-like objects. Actually, crows aren’t alone—other bird species have been seen pulling strings for centuries [1]. Anyway, crows use their beaks and feet to accomplish tasks with sticks and strings.

crow with a stick

a crow with a stick

crow incrementally pulling up a string to get food

a crow incrementally pull-stepping a string to get food

Presumably there is some range of dimensions and appearances of sticks and strings that a crow can:

  1. Physically manipulate
  2. Recognize as an affordance

And note that those items are required regardless of whether crows have insight at all or are just behaving through reinforcement feedback loops [1].

Organisms fit into their niches, but there’s flexibility to the fit. However, these flexibilities are not unlimited—there are ranges. E.g., physically a person’s hand cannot grip beyond a certain width. The discipline of Human factors (and ergonomics) studies these ranges of the human body as well as cognitive limits.

For an AI agent, there are a myriad places in which there could a function f and its parameter x with some range R of acceptable values for x. Perhaps the levels of abstraction for this to be useful are exactly those involved with perception of affordances and related skill-knowledge.


Polymorphic entities have the same interfaces. Typically one ends up with a family of types of objects (e.g. classes). At any given time, if you are given an object of a family, you can interface to it the same way.

In object oriented programming this is exemplified by calling functions (aka methods) on pointers to a base class object without actually knowing what particular child class the object is an instance of. It works conceptually because all the child classes inherit the same interface.

For example, in C++:

class A {
    virtual void foo() = 0;

class B : public A
    void foo() { std::cout << "B foo!\n"; }

class C : public A
    void foo() { std::cout << "C foo!\n"; }

void main() 
    std::unique_ptr<A> obj(new B);
    obj->foo(); // does the B variation of foo()

    std::unique_ptr<A> obj2(new C);
    obj2->foo(); //does the C variation of foo()

That example is of course contrived for simplicity. It’s practical if you have one piece of code which should not need to know the details of what particular kind of object it has—it just needs to do operations defined by an interface. E.g., the main rendering loop for a computer game could have a list of objects to call draw() on, and it doesn’t care what specific type each object is—as long as it can call draw() on each object it’s happy.

So what the hell does this have to do with mental development? Well, it could be a way for a mind to add new functions to existing concepts without blowing away the existing functions. For instance, at a high level, a new skill S4 could be learned and connected to concept C. But concepts S1, S2, and S3 are still usable for concept C. In a crisp analogy to programming polymorphism, the particular variant of S that is used in a context would be based on the sub-type of C that is perceived.

On the other hand, polymorphism could be fuzzier and more like the switch concept I mentioned in a previous post. In other words, the mechanism of the switch could be anything. E.g. a switch could be influenced by global emotional states instead of the active sub-type of C.

One can imagine polymorphism both at reflexive levels and on conceptual symbol-based levels. Reflexive (or “behavioral”) networks could be designed to effectively arbitrate based on the “type” of an external situation via the mapping of inputs (sensor data) to outputs (actuators). Conceptual based mental polymorphism would presumably actually categorize a perception (or perhaps an input from some other mental module) which would be mapped by subcategory to the appropriate version of an action. And maybe it’s not an action, but just the next mental node to visit.

[1] Taylor, A., Medina, F., Holzhaider, J., Hearne, L., Hunt, G., & Gray, R. (2010) An Investigation into the Cognition Behind Spontaneous String Pulling in New Caledonian Crows. PLoS ONE, 5(2). DOI: 10.1371/journal.pone.0009345

Image credits:

  1. University of Oxford
  2. David Schulz

Tags: , , ,

Heterarchies and Society of Mind’s Origins

Posted in artificial intelligence on February 4th, 2014 by Samuel Kenyon

Ever wonder how Society of Mind came about? Of course you do.

One of the key ideas of Society of Mind [1] is that at some range of abstraction levels, the brain’s software is a bunch of asynchronous agents. Agents are simple—but a properly organized society of them results in what we call “mind.”



The book Society of Mind includes many sub-theories of how agents might work, structures for connecting them together, memory, etc. Although Minsky mentions some of the development points that lead to the book, he makes no explicit references to old papers. The book is copyrighted “1985, 1986.” Rewind back to 1979, “long” before I was born. In the book Artificial Intelligence: An MIT Perspective [2], there is a chapter by Minsky called “The Society Theory of Thinking.” In a note, Minsky summarizes it as:

Papert and I try to combine methods from developmental, dynamic, and cognitive psychological theories with ideas from Artificial Intelligence and computational theories. Freud and Piaget play important roles.

Ok, that shouldn’t be a surprise if you read the later book. But what about heterarchies? In 1971 Patrick Winston described heterarchical organization as [3]:

An interacting community of processes, some narrow experts, others broad generalists, and still others in the role of critics.



“Heterarchy” is a term that many attribute to Warren McCulloch in 1945 based on his neural research. Although it may have been abandoned in AI, the concept had success in anthropology (according to the intertubes). It is important to note that a heterarchy can be viewed as a parent class to heirarchies and a heterarchy can contain hierarchies.

In 1973 the student Eugene Freuder, who later became well known for constraint based reasoning, reported on his “active knowledge” for vision thesis, called SEER [4]. In one of the funniest papers I’ve read, Freuder warns us that:

this paper will probably vacillate between cryptic and incoherent.

Nevertheless, it is healthy to write things down periodically. Good luck.

And later on that:

SEER never demands that much be done, it just makes a lot of helpful suggestion. A good boss.

This basic structure is not too hairy, I hope.

If you like hair, however, there are enough hooks here to open up a wig salon.

He refers to earlier heterarchy uses in the AI Lab, but says that they are isolated hacks, whereas his project is more properly a system designed to be a heterachy which allows any number of hacks to be added during development. And this supposedly allows the system to make the “best interactive use of the disparate knowledge it has.”

This supposed hetarchical system:

  • “provides concrete mechanisms for heterarchical interactions and ‘institutionalizes’ and encourages forms of heterarchy like advice”
  • allows integration of modules during development (a user (the programmer) feature)

One aspect of this is the parallelism and whether that was actually better than serial methods. The MIT heterarchy thread eventually turned into Society of Mind, or at least that’s what Patrick Winston indicates in his section introduction [2]:

Minsky’s section introduces his theory of mind in which the basic constituents are very simple agents whose simplicity strongly affects the nature of communication between different parts of a single mind. Working with Papert, he has greatly refined a set of notions that seem to have roots in the ideas that formerly went by the name of heterarchy.

Society of Mind is highly cited but rarely implemented or tested. Reactive aka behavioral robotics can be heterarchies, but are either ignored by AI or relegated to the bottom of 3 layer architectures for robots. The concepts of modularity and parallel processing have folded into general software engineering paradigms.

But I wonder if maybe the heterarchy concept(s) for cognitive architectures were abandoned too quickly. The accidents of history may have already incorporated the best ideas from heterarchies into computer science, however I am not yet sure about that.


[1] M. Minsky. The Society of Mind. New York: Simon and Schuster, 1986, pp. 249-250.
[2] P.H. Winston & R.H. Brown, Eds., Artificial Intelligence: An MIT Perspective, vol. 1, MIT Press, 1979.
[3] P.H. Winston, “Heterarchy in the M.I.T. Robot.” MIT AI Memo Vision Flash 8, March 1971.
[4] E.C. Freuder, “Active Knowledge.” MIT AI Memo Vision Flash 53, Oct. 1973.

Image Credits

  1. Samuel H. Kenyon’s mashup of Magritte and Agent Smith of the Matrix trilogy
  2. John Zeweniuk


Tags: , ,