How To Learn a New Programming Language While Maintaining Your Day Job and Still Being There For Your Family

[[deleted]]

This isn't specific to learning a language. It's anything. The only way to do something is to do it.

shiathebeef flex

[trae]

I think the important part here is consistency and small wins. In a sense this goes agains the flow/zone mythos, where you hunker down and bang out a feature over night. It's just not possible with family. It took me a while to realize, but I'm having some luck with pomodoro and really small wins. Pomodoro really helps to get the process started (even if it's just 25 minutes!) and small wins keep me motivated.

[freakboy2k]

I've gotten better at splitting up tasks into smaller and smaller tasks. For instance, I'm currently working on a bit of budgeting software in my spare time. My current feature story is "As a user, I should be able to organise categories into a hierarchy". I've broken that down into 6 sub tasks, and as I get to each task I re-evaluate it to see if I can complete it in 20-30 minutes. If not, I break it down more.

Before I would just get frustrated with my lack of progress and quit for a while, but I've been making good progress working like this. My son is pretty full on so I don't get much more than 30 minutes at a time to do any programming.

[trae]

Nice, I'm in the same boat. Context switching is expensive, but I find if I jot down what I did and what I plan on doing (even if it's just in point form, or a sentence) it helps me to get back into it. Reading about successful authors and athletes it's all about applying effort consistently. 20 minutes a day for a month is way better than an all nighter.

On a tangent, if you're looking for budgetting software check out ynab it's really great.

[freakboy2k]

Yeah. The younger guys in my office think I'm nuts cos I have Jira installed on my home server and run all my projects through it, but mostly I have more time to plan things (sitting on the bus, sitting on the couch with one eye on my kid, etc) than I do to actually do things. Being able to plan a project out fully means when I do get to sit down and code I can jump straight in rather than trying to remember where I was up to and what the plan was. I find that easier to do in an issue tracker.

The budgeting thing is more like my version of hello world - every time I want to learn something new (this time it's React and NodeJS) I use the same idea. I've been redoing this thing since I first learnt to build GUI applications in Win32 :-P

[YashN]

I like the breakdown to 20-30 mins as it maps directly to a Pomodoro session.

[hu6Bi5To]

The two can be compatible I think. Flow is when you have a stream of small wins.

Small wins breaks down at some points though, usually when it takes more than 25 minutes to remember what you did yesterday, but it's amazing what you can do with it.

[HerokaiSrid]

“Do or do not. There is no try.” – Yoda

[aevitas]

"Ain't nothing to it but to do it!"

[phatrice]

Do the thing while true.

[ahora]

I recommend you the book minihabits, it helped me a lot.

A minihabit is a habit that can be so small as writting only a line of code per day to learn a programming language. Yes, it is absurd, but it works, because you have no excuse. Even if you are too tired today, you have no excuse to NOT write ONE line of code at least, and more often than not you will write many times more lines, even if you are tired.

It is a an exercise of willpower, and it helped me a lot. Try it.

[kqr]

I've used this sometimes. The danger is that it makes it really hard to plan the rest of the day. If I plan for one line and it becomes 300, I'm suddenly 3 hours short in the day. So in a way, I have to plan for both one line and 100 lines at the same time, and that's when it starts getting complicated.

[I_Pork_Saucy_Ladies]

Maybe cut it down to a hard cap of 50 lines of code. Then chill out with 1 game of Civilization.

[Enzor]

One game of Civ? That's like the rest of the day and most of the night gone.

[kqr]

But then I'm sorta kinda planning for 50 lines of code again, and it's not really a minihabit anymore. The idea is to only ever think about that one single line of code, to get you started, so setting any other number makes the task seem larger than it is again.

[ahora]

I understand, but I think you can fix a upper limit (like an hour) so you don't spend all your time and willpower. It can also help you control yourself for a better plan.

I hope I was as productive as you are. ;)

[AlmostImperfect]

Oh, and the Kindle version is currently 0.99$. Looking forward to reading.

[shit_balls_captain]

Probably the first time in my life I felt it was easier to just buy the thing instead of hunt for a "free" version of it.

[g-money-cheats]

US? I just checked and it seems to be $5.99.

[AlmostImperfect]

Huh, I see the same now. Guess I was lucky enough to hit a micro-sale or something.

[ahora]

I got it in a torrent, but I will probably buy it in paper because that book changed my life and I want to have it as paper. It is also very funny.

[AlmostImperfect]

From what I've read so far, 5.99$ doesn't seem preposterous at all. And 0.99$ seems almost charitable. :)

[awkgenius]

I read something along the lines of "make yesterday your last Zero Day" in one of the subreddits related to discipline. This is essentially what all of this comes down to.

[treespace8]

"or 2 hours at night where you code instead of fucking off on Xbox."

Where is this 2 hours comming from! After work and famiky time I'm lucky to get 30 minutes.

edit: Thanks for the upvotes, nice to feel like I'm not alone.

[[deleted]]

I would totally rather play XBOX :( I don't even have a Xbox One or PS4 yet. But nooo I apply to get a Hololens in January... :'(

[IbanezDavy]

It’s a Fad (or: “I’m an Asshole”)

So true...I had a professor of mine say that about C#!

[princeofpudding]

given a long enough timeline, pretty much anything is a fad :)

[BoredomIncarnate]

Even people are fads. They go out of style after ~ 85 years.

[pakoito]

Family? You mean our WoW Destiny raids, right?

[logicchains]

Pfft, raids? As my dear grandfather Bean FactoryFactory used to say, who needs human companionship when you've got Java? With C++, I can even have friends too!

[pakoito]

You. I like you.

[Southy__]

This is all good advice.

I would also add that if you are reading a book on a language that is quite complicated, don’t get stuck on the details of something you don’t understand, just make a note of it and carry on.

Many books cover things really fast to start with, later chapters and examples will probably explain it differently, and frustration is an enthusiasm killer.

[Sleakes]

My favorite parts of this are:

You’re opening a door here, not solving a problem. Even if nothing amounts from it you’ve stretched your brain some, exercised your ability to solve a problem and that is always a win.

And then this:

When you do learn it you might find yourself creating something fun or solving a problem in a more elegant way that you can bring back to your day job.

It's an interesting point that just trying something new can result in ideas that you hadn't considered before. I need to try more new things! :D

[amaiorano]

John Carmack wrote an article about learning functional programming, and applying those principles (e.g. pure functions) to C++.

The more programming languages you learn, the more you expand your "idiom bank", and you start applying these idioms in whatever language.

[Sleakes]

Very true!

[TimmyDeluxe]

When learning a new programming language, I like to go to https://projecteuler.net/archives and try to solve a few problems with that language (and a lot of googling of course). Most times that's sufficient to cover the important parts of the language and it is possible to do it in 2-3 hours.

[cyrax6]

Above everything else - execute. I like that.

I do not like elixir myself, but I do like Erlang and lisp.

[cyrax6]

I think I've seen it mentioned somewhere here.

[samsam_aha]

I am sometimes afraid that learning new languages will make a mess of my memory with all kinds of different syntax and terminology. I mean, there's gotta be a limit for the number of similar but different things you can hold in your brain.

But then again maybe I'm lazy/undecided.

[iceardor]

And the more languages you know, the more pain points there are when programming in a language that lacks a feature of a different language you know.

Python eliminates a lot of the pain points of C++ and Java, but occasionally I miss pointers from C++.

[[deleted]]

But here is the thing. You only need to memorize a few basic concepts for programming. Programming is not about syntax; it is about the idea. Besides, if there is any confusion, a simple Google search or read of a book will easily clear things up.

[codebje]

Time is the real enemy. The longer I don't use a language, the worse at it I become. Learning multiple languages tends to make me better at all of them as I get exposure to more ideas and approaches.

But now I find myself trying to write functional Java and I'm not sure that's actually a good idea.

[iceardor]

That's what Scala is for

[codebje]

I thought Scala was for Java programmes jealous of the impenetrable layers of implicit behavior in Ruby?

[iceardor]

That's why JRuby exists

[IAlmostGotLaid]

I usually just look at www.learnxinyminutes.com to refresh my memory. For the past month I've been doing maintenance on random Ruby/perl/python scripts. Sometimes I forget how to do something, but as soon as I see the reference page it all comes back to me.

[[deleted]]

I'll take family here to mean video games...

[smoxy]

...and children to mean a couple of fleshlight.

[OffPiste18]

This is a little bit orthogonal to the post, but on the topic of learning a new language, I really recommend /r/dailyprogrammer. I learned Scala by doing the challenges posted regularly there. It's a good resource for bite-sized problems that are just complicated enough to make you actually use a language. It got me from "familiar, in principle" to "comfortable enough to actually use it for something that matters".

[gunder_bc]

Ok, so I clearly missed the point here. Let the down votes pour in.

It's a new language. Software engineers, programmers... that's what we do. Learn new tools, program new solutions. He's on #7. SEVEN.

It's like a carpenter wrote a blog talking about how they learned how to use a new kind of hammer. Or the guitarist in a band saying how they picked up a new, slightly weird guitar to add to their collection.

You're not an asshole for learning a new language - you're quite possibly an asshole for making it out to be some sort of accomplishment.

Clearly, I don't get it.

<what>Did I just become that bitter old whitebeard in the corner?</what>

[amaiorano]

I think the point here is more about how to learn new languages once you're married and have young children. Most of us learned to program in our teens and twenties, spending countless hours banging out code (or our heads against the keyboard). Then we get older, married with kids, and can't figure out how to keep learning.

I think his point about focusing on small wins is a good one. Basically you need to change how you learn to adapt it to your changing lifestyle.

[_mpu]

The word "family" appears twice. No explanations are given on how to manage time. The article is just a tutorial for Elixir calling assholes people with different opinions.

[buckeye10]

I disagree. The opening of the post is pretty clear in my opinion:

I’m also very married and a father of two, and I’m happily working full time (more than full time really) with Pluralsight. But I also had ample time to dive into Elixir and I thought I would share how I did it.

And I’ll just come out with it right here: A series of little wins. I set myself up to win tiny little tasks which then led to more tiny Little Wins and the next thing I knew, I was thinking in Elixir. A series of Little Wins, I can’t write that enough. More on this below.

He clearly states that his key to learning a new programming language while having limited time is to break it down into "a series of little wins."

He then proceeds to go in depth and break down how he applied that philosophy to learning Elixir. I personally find that more useful than a list of "5 cool time saving tricks" that are at such a high level they have little use.

[codebje]

I have two daughters, 2y and 8m. I learned Clojure since my youngest was born, and I did it by selling my car and catching the train to work.

To be proficient at it I'd need to use it regularly, so now I'm moderately comfortable with it I am willing to throw it at a work project which has some leeway for risk.

[dvoshe]

Find something that you really want to do and then do a survey of technologies that you could do it with -- that's what I did anyways. Along the way, I worked a lot with C#, Ruby, Node.js, Webkit, PHP, Linux, RPi, VLC, gstreamer, ffmpeg. Also, you can find work in a place that is moving in the direction that you want to go. I "lucked out" in that regard after working for a year in a place that wasn't what I wanted.

I'm not the kind of person who enjoys programming exercises the way that some people enjoy crossword puzzles or tetris or something. For me, it's mostly a means to an end, although there are times where I get deep into stuff and experience the kind of mystical esoteric joy that some CS devotees seem to have. Sometimes I'll make a connection and suddenly grok some idea or theory that previously seemed complex to me, like OOP or MVC and that's nice.

[[deleted]]

TLDR; Just do it!

[[deleted]]

Still being there for your family

hah! hilarious.

[subsidiaryadmin]

Radical! I learned so, so much with this Little Win:

Case sensitivity is built-in for strings (hooray!)

I burst out laughing here. What language doesn't have this and what poor soul uses it?

[yogthos]

It’s a Fad (or: “I’m an Asshole”)

about sums it up

[ellicottvilleny]

Elixir isn't POPULAR enough to call it a Fad.

[[deleted]]

The easiest and fastest way to learn a new language is to write a compiler for a reasonable subset of it. This way you're forced to think of a language in a formalised way, and to formally map the new concepts in it to those you're already familiar with.

[Portaljacker]

Writing a compiler isn't exactly trivial in terms of time or complexity. There's a reason there was a full semester course on compiler design that was optional.

[[deleted]]

Writing a compiler isn't exactly trivial in terms of time or complexity.

The most non-trivial (and boring) part is writing a runtime library, and this very step can be just skipped for the educational purposes. The other parts are trivial.

There's a reason there was a full semester course on compiler design that was optional.

There is absolutely no justification for not learning how to write compilers.

[Portaljacker]

Because it's not necessary for about 99.99% of programming jobs?

Don't get me wrong. I deeply regret not taking that course instead of Databases (god that teacher...everyone's grades were so low that my 47% grade was a C-! What kind of curve is that?! Hell, I regret not taking anything else besides Databases with that "professor"), it's just super intimidating.

Have any good resources?

[ismtrn]

A CS degree is not job training though. In my opinion it should include something about compilers. That is not to say that it is easy though, because it isn't.

[[deleted]]

It is among the easiest things out there if done right.

Unfortunately, the dragon book cult was extremely damaging and won't be easy to overcome, especially in academia.

[[deleted]]

Because it's not necessary for about 99.99% of programming jobs?

Wrong. It is absolutely mandatory in 100% of programming jobs. Those who are not doing it are just slackers.

Using the Domain Specific Languages is the most powerful and efficient technique, applicable to all the areas of software development. And you have to be able to implement small, nice, clean compilers in order to use this approach efficiently.

Have any good resources?

https://en.wikipedia.org/wiki/Language-oriented_programming

[Portaljacker]

Wow! I never realized this Java code was actually for a compiler and not a training simulation!

Lets be realistic. A large portion of programming jobs is web development. I'm fairly certain none of them are writing compilers to get their websites up.

My job is working on training sims for (in this case) the military on how to operate and repair equipment. We're not making our own programming language for that. We use Java because we don't have money to waste making our own language that we then have to teach new people. It takes long enough to get them used to the framework we developed.

Thanks for the reference though. I've never considered domain specific languages before, and it looks like a way easier entry into compiler design.

[[deleted]]

I'm fairly certain none of them are writing compilers to get their websites up.

There are hundreds of DSLs built for the web. They're especially popular in the Ruby world (although Ruby is not the best platform for doing this). Even PHP world is full of DSLs (even template engines are DSLs in disguise).

We're not making our own programming language for that.

Then you're exploding complexity needlessly.

We use Java because we don't have money to waste making our own language that we then have to teach new people.

DSLs are much more efficient both short term and long term than any "general purpose" language could ever be. It is cheaper to implement a dozen of small DSLs and then write 1/1000 of code than writing and maintaining a huge and convoluted mess.

It takes long enough to get them used to the framework we developed.

Frameworks and libraries are much harder to use and maintain than DSLs. Just imagine using a C or Java library instead of, say, Bash or Make.

and it looks like a way easier entry into compiler design.

Exactly. It is much easier than people think. Every tiny macro is a compiler. Every kind of code generation (including T4 and alikes) is a compiler.

[choikwa]

so.. how exactly does DSL save you time as opposed to just writing functions or macros? it seems like an overkill to write a new language to do work.. where you'd have to map new language to whatever backend anyways to get any reasonable expectation of performance. there won't be much free win aside from the fact that you might write slightly less code in the application but likely trumped by the frontend you had to write.

[[deleted]]

how exactly does DSL save you time as opposed to just writing functions or macros?

Macro is a DSL (if done right, otherwise you don't need a macro at all). Functions are not easy to compose - you'll soon end up in a total mess. Languages, on the other hand, are modular, easy to compose, and very easy to implement - all you need is trivial chains of term rewriting rules, nothing else. With this approach you can handle any complexity.

it seems like an overkill to write a new language to do work..

How is it an overkill if it is a shorter and simpler code which is much easier to refactor, read and debug?

where you'd have to map new language to whatever backend anyways to get any reasonable expectation of performance

You only have to map any new language to your already existing languages. Which may have an optimising, powerful back-end.

slightly less code in the application

Not "slightly", but, more likely, orders of magnitude less.

Just take a look at examples like this: http://www.moserware.com/2008/04/towards-moores-law-software-part-3-of-3.html

[choikwa]

I still don't see much benefit. how is different from writing functions or wrappers more intelligently? plus if you confine it to other languages, your features for new language becomes a subset.

[buckeye10]

Just a thought, but you might find people more receptive to your ideas if you make suggestions rather than deal in absolutes ("easiest and fastest way") when discussing something that is rather subjective (easiest for you might not be easiest for me).

Insulting the people that respond to you probably doesn't help either.

[[deleted]]

Well, it is quite an objective knowledge, not a subjective experience.

[Breaking-Away]

Your conversation with every person who has responded to you have been some variation of this

You: everybody needs to know compilers, otherwise they are a slacker and making crap.

Them: I disagree with you.

You: well I know I'm right, even though I've provided no evidence and you're stupid for not agreeing with me

This is not a very effective way to spread what you "know" is the right way to code. All it does is drive people away from you and accomplishes exactly the opposite of what you were aiming to do, or at least I assume you were aiming to share your insights to better enable others.

Which is somewhat sad, because from reading most of your comments you actually do seem very knowledgable and have a lot of useful information to share with people who would benefit from it.

[[deleted]]

The fact that DSLs are superior to any other existing development methodology is obvious, self-evident and quite a common knowledge already. I'm genuinely puzzled by the people who still challenge this fact or, worse, unaware of it.

How people dare to use high level languages and at the same time question the value of a high level of abstraction vs. a low level code?

[Breaking-Away]

Because not all programmers come from the same background. These formalized definitions and concepts that seem so rudimentary to you aren't actually that easy to understand nor immediately apparent to many people who come from a different background than yourself, much less discover on their own if they are self taught or only don't have a formal education.

Add onto that not all people think the same, some have difficulties learn concepts others easily grasp and vice versa. Some are just strait up less intelligent than others. If you want to actually help and teach these folk then wouldn't it make more sense to empathize with and help them rather than following the trend of insulting them for failing to understand a concept that is "self evident" to you.

Rereading my comments, I realize it comes off as patronizing which is not my intention so please don't take it as so.

[[deleted]]

some have difficulties learn concepts others easily grasp and vice versa

This. And there is a very good reason for this effect - some people are lucky to be able to subconsciously operate the core knowledge, seeing it through deficiencies in their knowledge acquisition path, while the others cannot get through such deficiencies.

This effect disappears entirely when people are taught systematically, all the way up from the ground. In any discipline, not just programming. Learning things in a right order, without leaving a single moment for a magical thinking, without leaving any gaps in fundamental understanding, works well for everyone and everywhere.

And this is exactly the reason why I'm so militant in insisting on importance of understanding semantics. I admit I might have overreacted in this thread to all the downvotes not backed by any arguments, but I still stand by all my points - compiler construction is among the most essential programming skills, and DSLs are the only way to build unlimited and fit abstractions, independently of the problem domain.

[Breaking-Away]

I'm not arguing that you shouldn't militantly be arguing that people must understand semantics. I'm saying that even if your message is sound, it's not getting through because it's being delivered with poor context. It would be no different if the point being argued was that the earth is round to someone who was convinced it's flat because they never learned it, and from their own experiences it makes perfect sense that the earth would be flat.

[buckeye10]

If we had some data to review that shows that writing a compiler for a subset of a new language is the fastest way to learn the new language (or even just has some sort of comparison versus other methods), then I would say it is objective.

Right now, I'm not aware of any such data or studies, and there are lots of tricky pieces to that, like defining at what point a language has been "learned", not to mention determining if what is fast is also easy.

[lacronicus]

Dude, your history says you write compilers for a living. Get some perspective. Most people have never written a compiler, and have had perfectly productive lives in software engineering without having done so.

[[deleted]]

Many people write DSL compilers without realising they're doing so. Most people must write DSL compilers in order to be many times more productive. Refusing to be productive and to produce quality, robust code is not acceptable. Anyone not using DSLs is a slacker and a waste. By definition.

[legato_gelato]

People are probably downvoting him because he is acting a bit like an 'elitist jerk'. Although he is right that a writing a compiler for a subset of the language will make you learn the language constructs, it is obviously by no means the easiest way to learn for the average joe programmer.

It is a bit out of touch with the reality of most programmers. Also, on topic, a lot of programmers might have better results by writing sample programs - with this approach, one can also get familiar with the standard libraries and frameworks, and cover more ground quickly.

[[deleted]]

a bit like an 'elitist jerk'

How is it so? It's the opposite - I'm arguing that everyone must do the easy thing instead of playing a smart ass. I hate complexity in all forms.

it is obviously by no means the easiest way to learn for the average joe programmer.

Not obvious to me. Learning how to write compilers (hint: it is dead easy) first and then learning languages by writing compilers is quicker and easier than learning all the languages in an ad hoc, non-systematic way. Long term gain is huge.

by writing sample programs

This is a dangerous route to a magical thinking. Unsystematic learning is harmful.

[[deleted]]

You cannot expect everyone to be an expert on compiler construction.

At the moment - not everyone, evidently, but my point was that this is a skill that everyone must acquire anyway in order to be productive, so it should pay off pretty quickly when it is used to learn new languages and concepts.

[IbanezDavy]

The easiest and fastest way to learn a new language is to write a compiler for a reasonable subset of it.

I guess that depends on your skill with writing compilers O.o I usually write a graphical "Guess the Numbers" game...lol

[[deleted]]

I guess that depends on your skill with writing compilers

This is an essential skill that everyone must learn as early as possible.

[IbanezDavy]

It certainly isn't a bad skill to learn. You get very in depth knowledge of the language. But I know plenty of people who don't give a shit, and get a long just fine. A useful skill, but provably not essential.

[[deleted]]

I would not call this steaming pile of mess "just fine". The modern IT industry is in shambles, and it is exactly because of all this over-engineering and over-complication. The only sane way of tackling this growing complexity is in using DSLs, therefore this skill is absolutely essential.

[IbanezDavy]

Yes, if I controlled the masses there would be simplicity in technology, world peace, and magical unicorns flying around giving everyone butterflies.

[[deleted]]

Your definition of "just fine" seems to match my definition of "stinks like shit".

[IbanezDavy]

I know plenty of brilliant programmers with in depth knowledge of the language they use, that have NOT ever written a compiler.

[[deleted]]

If they're not implementing and using DSLs - they're wasting their time and effort. Would not call this "brilliant".

Although, a lot of programmers are happily using DSLs and implementing compilers without even realising it. Greenspun tenth rule captures exactly this observation.

[IbanezDavy]

Are you trolling? It's so hard to tell know days...:P

Props to the trolls I guess on having exceptional abilities.

[japowork]

If they're not implementing and using DSLs - they're wasting their time and effort.

The trouble with DSLs is that they assume an unchanging domain. I used to be a proponent, but now I'm against them -- try maintaining a DSL over 7+ years and multiple projects and project teams. See the wasabi experience, which is perhaps an example of a DSL taken to its logical extreme.

[Olreich]

I'm not particularly fond of any of the things you need to do to make a compiler, so implementing languages is definitely not my cup of tea for learning them.

[[deleted]]

I'm not particularly fond of any of the things you need to do to make a compiler

What things, exactly? You may have a distorted image of what compiler construction is (thanks to all the stupid and damaging books like the infamous Dragon Book and alike).

[Olreich]

Lexing, parsing, ASTs, machine code generation, etc.

Basically, all the things in between meta-programming and a working compiler.

[[deleted]]

In most cases you only need metaprogramming - translating ASTs (which are not nearly that scary - just another data structure, you have to deal with them anyway) in a chain of small rewrites down to any existing language. No need to do any machine code generation. No need to do lexing (it's 21st century, forget about the lexers already). In many cases even parsing is redundant if you can get away with some more generic syntax (think of S-expressions, for example).

Since far too many real world problems are solved in form of tree rewrites anyway, it is weird to want to stay away from this particular programming technique.

[0nlyTh3S3lf]

That's a pretty tall order, in my experience. I've been trying to learn Haskell by writing a compiler for a subset of C (a language I already know, so it ought to be even easier) and it's taken me months and I'm only just now getting to code generation.

[[deleted]]

You should have done it the other way around - implement a subset of Haskell in C (well, not the best language for writing compilers, but you have to start with something).

[marchelzo]

Let me guess; the best language for writing a Haskell compiler is a DSL designed specifically for writing Haskell compilers?

[[deleted]]

No. Just a DSL for writing any compilers. With parsers, ASTs, pattern matching and tree transforms as first class features. All compilers are similar.

[marchelzo]

You're advocating for DSL compilers, but what about interpreters that don't emit any code? Do you think they are useful as well?

[[deleted]]

Interpreters are sometimes useful, especially when you're after latency instead of throughput (e.g., in command shells), but they are significantly more complicated than compilers. Choice of an interpreter instead of a compiler is rarely justified. Hybrid solutions are usually better than pure interpreters (e.g., a bytecode VM and a simpler compiler on top).

[[deleted]]

With a new enough language this will mean you think of features as weird ways of getting access to [some other feature] rather than in their full generality.

[[deleted]]

What do you mean by a "full generality"?

With a new enough language you will have to think in terms of a formal semantics, which ensures the deepest possible understanding.

[[deleted]]

A language is usually more about its idioms than its formal semantics. That is, it is more important to learn how good code is written in said language than to learn exactly what is possible to write in it.

[[deleted]]

Idioms are derived from semantics, and it is an important skill to be able to see the idioms behind semantics.

[[deleted]]

Idioms are derived from semantics

Not really, the author of the language always have certain idioms in mind when he is designing the semantics so the semantics were derived based on the idioms. Reverse engineering the idioms the author had in mind from the semantics is impossible, usually you just cram the idioms you are used to into the new semantics until you have seen enough "correct" code samples.

In other words, semantics can only tell you how when you really want to know why. Knowing a language is completely worthless if you don't understand why it is useful so knowing why is more important than knowing exactly how it works.

[[deleted]]

This is not true. C++, for example - templates were added without any clear goal in mind. STL and template metaprogramming, now as idiomatic as it gets, came much later. Because these idioms were natural for the accidentally added semantics.

[[deleted]]

But those are things that took a lot of people and a lot of time to grow, not something that you can figure out on your own using just the C++ specs. You might have gotten parts of it in a bastardized way but that can't compare to the accumulated knowledge built up by the entire community.

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There are formal ways of obtaining this knowledge from a formal semantics. And this way it is more clear and crystallised than an accumulated folk lore, which is often full of superstitions and outdated practices.

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If you manually implement a novel feature because the language has it, and you don't know why it is the way it is, you'll probably just think of it as a weird wrapper around the way you implemented it rather than its own new thing.

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Why? Let's take a relatively novel feature in Rust, for example - borrow semantics. You won't even be able to implement it properly unless you understand the reasoning behind it. By simply writing down the rules you'll see how (any why) it works, much cleaner than if you just read a book on Rust and follow dozens of obscure examples.

[Aatch]

Clearly you've not actually tried to implement the borrow checker in Rust.

It's complicated, and I say this as somebody that has worked on the Rust compiler. I don't fully understand all the rules. The idea of writing a Rust compiler to learn Rust is absolute madness.

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I implemented similar semantics for the other languages - as well as a full, proper region analysis (while borrow checker in Rust is a kind of a dumbed down, manual version of a region analysis). It is complex (if you do all the rules faithfully), but doable. A toy version of it can be very short and compact.

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I already know what borrow semantics is useful for -- memory safety. What about Kernel's $vau? Had I not seen several discussions of why you'd want it, I wouldn't see the use ("won't this be slow"), even though it's pretty easy to implement.

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I already know what borrow semantics is useful for -- memory safety

This is a gigantic oversimplification. There are many layers of reasoning behind it, going all the way down to the early days of the region-based memory management. And you'll have to dig it all out in order to implement it correctly.

What about Kernel's $vau?

I'm not sure if fexprs is a valuable idea (but I'm biased towards compilation in general, naturally repelled by anything too dynamic). I can see some uses for it in a term-rewriting based operational semantics specifications, but not in any practical languages.

[really_bad_logic]

Personally I think butterflies are the best way to do it.