tl;dr Prolog gave me a whole new perspective. Let me know programming languages that altered how you attack a problem!
Backstory
Introduction to the language
I was in my second year of University studying Computer Science. I'd caught wind that the programming language for the Artificial Intelligence module wasn't a language we'd covered so far in the degree. I was excited, I thought I'd already gotten a decent grip on C, C++, Python, and Java so I was ready for anything. 😬
"Your first assignment will be to create an AI using Prolog".
What the fu*k is a Prolog were my precise thoughts. I thought I was pretty clued up on all the programming languages out there. Why are we learning a programming language I've never even heard of?
I went home, did some googling to try to find out what this Prolog thing was.
"Prolog is a logic programming language associated with artificial intelligence and computational linguistics". Right, AI, that's probably why we're learning it, or is it because the language was made in Marseille, France, and my Lecturer is French? 🤣
The following week we had our first introduction to the language, I quickly realised that no matter how well I knew C, C++, Python or Java it was not going to help me in understanding Prolog. It took me no time at all to grow hatred towards the language. It just doesn't. make. sense.
I went through countless tutorials, tried tonnes of example problems, took apart people's solutions to problems line by line, it just wasn't going in. I would take apart some code and trick myself into thinking I understood how it worked but when it actually came to coding in Prolog myself, my brain stopped.
Salvation
I'd had enough of struggling with Prolog. After I'd exhausted all possible avenues on the internet to learn it I'd decided to actually listen to my Lecturer and get the recommended book.
Prolog Programming For Artificial Intelligence - Ivan Bratko. This book changed everything. I pretty much devoured the book in a day. I was hooked, the book had me wanting more. I went back to the coding problems I'd struggled on just a day before and could think of 20 different ways to solve it, I began to LOVE the language. In class, I went from the student who condemned everything about the qwerky language to Prologs biggest advocate.
What is Prolog?
Prolog is a logic programming language. You define relations which are known as Facts and Rules. You then query your knowledge base and it returns the output based on those facts and rules. Solutions are typically written by recursion, the program calls itself until some objective has been satisfied, which is often referred to as the base case or final state. Backtracking is another important feature of the language: when a subgoal is not satisfied prolog backtracks meaning it traces its steps backwards to the previous goal and tries to satisfy it.
What's so special about Prolog?
Prolog is one of those very rare languages where I'd say that a non-programmer would likely have as good as or if not better experience understanding it than a programmer. See us developers are so accustomed to imperative programming, telling the compiler what we want to happen, step by step. When we're forced to think declaratively (Writing code that describes what we want, our desired result but not necessarily how to get it) it hits our brains for six, well, mine at least.
Prolog gave me a whole new way of looking at a problem, it made me ask different questions. Rather than asking what is the next step, I think of the desired state and the processes involved to get to that state.
If you have a programming problem and you were tasked to solve it in 3 different languages be it Java, C#, C++. It is very likely that you would solve the problem pretty much exactly the same in each, taking the same steps to manipulate the input to get the desired output. Yes, I get you'd probably use different constructs of each language but likely the general approach would be the same. However, if you learn Prolog you can ask yourself "How would I solve this in Prolog". And although attempting to map your Prolog solution to that of an imperative solution might not necessarily be the best approach, it opens avenues for alternate possibilities and expands conceivable results.
Finally
This blog was really supposed to be a #discuss as I am mainly interested in hearing how learning new languages altered how you think about solving a problem. I know that learning Functional programming languages has profound impacts on some peoples outlook so I'd love to hear from you!
Follow me on twitter if you don't want to miss out on absolutely brilliant programming insight: 🤣 @luke_garrigan
Thank you, if you like my rambling check out my personal blogging site at https://codeheir.com/
Top comments (69)
Awesome post, I had contact with Prolog at my Computer Science course, I struggled a lot with it. Maybe it's time to go back to it with this book that you recommend to give it another try.
For me every programming language that I experienced changed my life in some aspect.
Each language exposed me to different ways of seeing things ☺
Very agree with you. Learnt foxpro and visual foxpro to understand more on data processing.
Learnt BASIC to know about structured thinking and modularity.
I don't have much time to study more. Now i want to learn python.
I glad i read this post on prolog, it challenged my mind and i appreciate this comment, it gives me insight on how the other programming languages bring impacts to you, at least for python. 😁🙏
Completely agree. It seems me and you have had very similar learning paths!
Great spirit we should always try to learn something new from a programming language.
Moreover, there's a language with syntax similar to Prolog, so learning Prolog might make it easier for you to learn the other one, too. Its name is Erlang and it's still used in production in many businesses.
Erlang (and OTP!) is nice indeed.
But the paradigm is different than Prolog's: in functional programming languages, you'll end up with a function you can call.
In Prolog - a declarative language - you'll end up with a bunch of predicates that can be solved. A system of (logical) equations that you can generate solutions for.
For anyone interested in knowing the business case for Erlang, WhatsApp uses it extensively. Might make a good case study!
It also powers newer versions of Chef Server.
Well as per this tweet Erlang powers more than 90% of Internet, once its in Cisco routers ;)
And now you have also Elixir, that runs on the same virtual machine, the BEAM.
Elixir is very cool, if I only had more time I'd be digging into it more!
I am playing now with it, and I am loving Live View :)
It seems that you work in embed systems, so you must already know the Nerves Project?
I have indeed! While I do have a few Raspberry Pis, I would like to see if I can get it running on some other boards...NXP makes some ARM Cortex A7 microcontrollers that should have enough memory to run this, and the Nvidia Jetson is another candidate. It will be quite an adventure porting it to a new platform, but I will definitely learn a lot!
Did not know about live view, very cool! I haven't played around with the web framework at all, but it looks really cool.
In the words of Joe Armstrong, anything have enough memory to run Erlang/Elixir/Nerves, and this his because Erlang was made 30 years ago, and on that time computer where not having the processing power of this cheap boards.
I need to start playing with this boards to, must be a lot of fun ;)
It's a big thing to replace Single Page Apps in a lot of use cases.
ooh lovely, sounds like a weekend challenge!
There's also Elixir which another language that runs on the Erlang VM, a bit similar to Prolog. But, If you wanna learn Erlang checkout out this book: learnyousomeerlang.com/content
Elixirs syntax is little nicer than Erlangs. Both of these are interoperable, they work on the same virtual machine called BEAM. And what they excel - are concurrency and resilience. They (elixir and erlang) are awesome candidates for languages to learn in the age of microservices.
One of the bigger recognizable companies that use Elixir is Discord. And Ericsson uses Erlang, but they are not as sexy ;)
Discord guys have a blog on Medium and it's pretty interesting.
Clarifications here though I'm a noob at Elixir. Elixir extends Erlang because you can invoke Erlang functions. Erlang was developed by Ericsson and is used for running the cellphone towers insuring uptime which also I think makes it great for microservices.
Honestly, I crap on Javascript a lot (sorry!), but it was the first language that gave me the freedom to explore and the autonomy to have fun with software... and it’s that freedom and fun that has kept me invested as a developer all those years!!! 🥰😍
Haha love this, we all crap on Javascript but we all seem to use it 😂 and secretly love it really!
I had the privilege of being taught prolog by prof. Bratko. He had a knack for explaining problems so that everyone understood them, no matter the diffuculty.
Oh wow that’s amazing! I envy you, his book completely saved me. What a guy.
Lisps. All of them. Scheme changed how I write JavaScript (and any language with functions), Common Lisp changed the way I think about programming - literally. I see more languages that read themselves instead of machines that do stuff. It was weird. It still is.
This is why I can't keep my eye off projects like Nim and Julia. They somehow managed to ALGOLize lisp-style metaprogramming.
Yes, these two are doing it right, and is a very unfortunate myth that you need S-expressions in order to do an AST-level metaprogramming comfortably.
I even demonstrated it with a C syntax, just for giggles: github.com/combinatorylogic/clike
You have my attention 😄
Feel free to browse that project and everything else there, pretty much all the stuff I'm working on is related to static metaprogramming one way or another. Also, take a look at the generated docs and a small tutorial
Lisp! Emacs!
I still am totally surprised when I explain "but you can totally rewrite the editor while it's running" and most Software Engineers just blink at you as if you said "THE MOON IS MADE OF COWS" or something similarly weird and non-sensical.
Python tuples and sets made immutability and typescript enums make a lot more sense to me.
Good post! It's good for experienced coders to remember what it's like to be totally lost when learning. We take a lot for granted working in similar languages so often
I "learned" Prolog in school. We were about it for about half a year in our CS course. And I was fascinated with the language and I did not have the same issues as you had, but that may be, because I was not yet firmly into imperative programming.
On the other hand, after some more years, when I was firmly in the grasp of IP and I was learning C# 4.0, it was lambdas and Linq2SQL, that were very hard on my brain.
Now I really like them and when I was dabbling a bit into F#, my first thought was just "Oh ... everything is a lambda here".
Very interesting post. When I started my classss for computer sciences back in 1988, for few weeks I wasn't even comfortable touching the computer. Eventually the same field changed my life and I was considered a very good developer. Then came the change of era from procedural languages to OOP with GUI based interfaces to write software in VB, I lost it there and could not handle OOP concepts with such a programming interface. Anyway, ky career never required me to ever worry about writing code anymore. But I guess once a programmer always a programmer. I developed that itch lately for writing software and I realized I am way behind and all of this is completely new to me. Lately I have started reading again and took Python as first one to get myself comfortable. Reason was that while it has OOP concepts, it also has a procedural language style. Not sure if all this would bring some change in my life or not (_)
Thank you for your comment. I have had the same thought about moving from a programming job into a management role, I think I'd really miss coding!
At the age of about 50 where I have seen great success in my career working in senior management roles for fortune 100 companies, I still feel that I took up management roles very early in life.
My first and foremost language was Ruby. Probably if not Ruby I wouldn't even bother learning programming but I was so captivated and inspired by Ruby code, its elegance and expressiveness coupled with interesting "everything is an object" model that I stick to it. Then I discovered Rails, web development and things got rolled further!
Its worth noting that Prolog and SQL actually have a LOT in common. Both are declarative languages structured around tables of fact tuples and relationships between them. And then you give it a specification and it returns a set of tuples that match the specification. Prolog of course does a whole lot more (and it perhaps does it an injustice to make the comparison), but if you really boil down to it, the two are very similar. It'd be nice if makers of new databases had another look at prolog. If you wanna go 'past' SQL, maybe Prolog is in fact the future!
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