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I'm working on a fairly simple text-editor for Haskell, and I'd like to be able to highlight static errors in code when the user hits "check."
Is there a way to use the GHC-API to do a "dry-run" of compiling a haskell file without actually compiling it? I'd like to be able to take a string and do all the checks of normal compilation, but without the output. The GHC-API would be ideal because then I wouldn't have to parse command-line output from GHC to highlight errors and such.
In addition, is it possible to do this check on a string, instead of on a file? (If not, I can just write it to a temp file, which isn't terribly efficient, but would work).
If this is possible, could you provide or point me to an example how how to do this?
This question ask the same thing, but it is from three years ago, at which time the answer was "GHC-API is new and there isn't good documentation yet." So my hope is that the status has changed.
EDIT: the "dry-run" restriction is because I'm doing this in a web-based setting where compilation happens server side, so I'd like to avoid unnecessary disk reads/write every time the user hits "check". The executable would just get thrown away anyways, until they had a version ready to run.
Just to move this to an answer, this already exists as ghc-mod, here's the homepage. This already has frontends for Emacs, Sublime, and Vim so if you need examples of how to use it, there are plenty. In essence ghc-mod is just what you want, a wrapper around the GHC API designed for editors.
Is there some graphical shell like ghci for Haskell and Linux? I know about Winghci and it is very good interpreter but it is Windows only.
Regarding "what does WinGHCi do that GHCi does not?":
The command prompt, user input and program output are different colours. I can't begin to tell you how helpful this is when you're scrolling through huge pages of text trying to find the last command you typed. I wish more Haskell programs would produce coloured output...
You can load files using an actual GUI, rather than having to memorise a 200-mile long file path.
It has a whole bunch of buttons and menu items for common operations, which can be useful if you're new to GHCi and don't know the corresponding command names.
On Windows, terminal windows look horrifyingly ugly, while WinGHCi does not. Whether this problem exists on Linux is a matter of opinion.
Regarding the actual question asked: I'm not aware of any nice GUI tool for GHCi on Linux. Probably the best you can do is use the Emacs operating system; I'm sure somebody will have built some kind of GHCi support for that by now...
ghci runs fine on Linux, although I don't know of any graphical versions of it.
A few options if you want more features:
Use a powerful terminal emulator
Integrate ghci into your editor with something like 'Emacs Haskell Mode' or 'SHIM for Vim'
Have you heard of HUGS ? I only used it for Windows, but on the website you can download it for some Linux distributions, too.
It's a long time ago since I used it, but as far as I can remember it was an easy to use but powerful and fairly good documented interpreter.
hope this helps
Is there a programming language which can be programmed entirely in interactive mode, without needing to write files which are interpreted or compiled. Think maybe something like IRB for Ruby, but a system which is designed to let you write the whole program from the command line.
I assume you are looking for something similar to how BASIC used to work (boot up to a BASIC prompt and start coding).
IPython allows you to do this quite intuitively. Unix shells such as Bash use the same concept, but you cannot re-use and save your work nearly as intuitively as with IPython. Python is also a far better general-purpose language.
Edit: I was going to type up some examples and provide some links, but the IPython interactive tutorial seems to do this a lot better than I could. Good starting points for what you are looking for are the sections on source code handling tips and lightweight version control. Note this tutorial doesn't spell out how to do everything you are looking for precisely, but it does provide a jumping off point to understand the interactive features on the IPython shell.
Also take a look at the IPython "magic" reference, as it provides a lot of utilities that do things specific to what you want to do, and allows you to easily define your own. This is very "meta", but the example that shows how to create an IPython magic function is probably the most concise example of a "complete application" built in IPython.
Smalltalk can be programmed entirely interactively, but I wouldn't call the smalltalk prompt a "command line". Most lisp environments are like this as well. Also postscript (as in printers) if memory serves.
Are you saying that you want to write a program while never seeing more code than what fits in the scrollback buffer of your command window?
There's always lisp, the original alternative to Smalltalk with this characteristic.
The only way to avoid writing any files is to move completely to a running interactive environment. When you program this way (that is, interactively such as in IRB or F# interactive), how do you distribute your programs? When you exit IRB or F# interactive console, you lose all code you interactively wrote.
Smalltalk (see modern implementation such as Squeak) solves this and I'm not aware of any other environment where you could fully avoid files. The solution is that you distribute an image of running environment (which includes your interactively created program). In Smalltalk, these are called images.
Any unix shell conforms to your question. This goes from bash, sh, csh, ksh to tclsh for TCL or wish for TK GUI writing.
As already mentioned, Python has a few good interactive shells, I would recommend bpython for starters instead of ipython, the advantage of bpython here is the support for autocompletion and help dialogs to help you know what arguments the function accepts or what it does (if it has docstrings).
Screenshots: http://bpython-interpreter.org/screenshots/
This is really a question about implementations, not languages, but
Smalltalk (try out the Squeak version) keeps all your work in an "interactive workspace", but it is graphical and not oriented toward the command line.
APL, which was first deployed on IBM 360 and 370 systems, was entirely interactive, using a command line on a modified IBM Selectric typewriter! Your APL functions were kept in a "workspace" which did not at all resemble an ordinary file.
Many, many language implementations come with pure command-line interactive interpreters, like say Standard ML of New Jersey, but because they don't offer any sort of persistent namespace (i.e., when you exit the program, all your work is lost), I don't think they should really count.
Interestingly, the prime movers behind Smalltalk and APL (Kay and Iverson respectively) both won Turing Awards. (Iverson got his Turing award after being denied tenure at Harvard.)
TCL can be programmed entirely interactivly, and you can cetainly define new tcl procs (or redefine existing ones) without saving to a file.
Of course if you are developing and entire application at some point you do want to save to a file, else you lose everything. Using TCLs introspective abilities its relatively easy to dump some or all of the current interpreter state into a tcl file (I've written a proc to make this easier before, however mostly I would just develop in the file in the first place, and have a function in the application to resources itself if its source changes).
Not sure about that, but this system is impressively interactive: http://rigsomelight.com/2014/05/01/interactive-programming-flappy-bird-clojurescript.html
Most variations of Lisp make it easy to save your interactive work product as program files, since code is just data.
Charles Simonyi's Intentional Programming concept might be part way there, too, but it's not like you can go and buy that yet. The Intentional Workbench project may be worth exploring.
Many Forths can be used like this.
Someone already mentioned Forth but I would like to elaborate a bit on the history of Forth. Traditionally, Forth is a programming language which is it's own operating system. The traditional Forth saves the program directly onto disk sectors without using a "real" filesystem. It could afford to do that because it didn't ran directly on the CPU without an operating system so it didn't need to play nice.
Indeed, some implementations have Forth as not only the operating system but also the CPU (a lot of more modern stack based CPUs are in fact designed as Forth machines).
In the original implementation of Forth, code is always compiled each time a line is entered and saved on disk. This is feasible because Forth is very easy to compile. You just start the interpreter, play around with Forth defining functions as necessary then simply quit the interpreter. The next time you start the interpreter again all your previous functions are still there. Of course, not all modern implementations of Forth works this way.
Clojure
It's a functional Lisp on the JVM. You can connect to a REPL server called nREPL, and from there you can start writing code in a text file and loading it up interactively as you go.
Clojure gives you something akin to interactive unit testing.
I think Clojure is more interactive then other Lisps because of it's strong emphasis of the functional paradigm. It's easier to hot-swap functions when they are pure.
The best way to try it out is here: http://web.clojurerepl.com/
ELM
ELM is probably the most interactive you can get that I know of. It's a very pure functional language with syntax close to Haskell. What makes it special is that it's designed around a reactive model that allows hot-swapping(modifying running code(functions or values)) of code. The reactive bit makes it that whenever you change one thing, everything is re-evaluated.
Now ELM is compiled to HTML-CSS-JavaScript. So you won't be able to use it for everything.
ELM gives you something akin to interactive integration testing.
The best way to try it out is here: http://elm-lang.org/try
I recently started picking up vi, going through some tutorials and trying to get used to it. But I still have some questions about it.
It seems to be nice for small one file changes, but as soon as I start to try doing bigger things it seems to be lacking. For example I'm used to have code formatting, import organizing, simple overview over all packages and other things that an IDE gives me. I saw some tutorials on how to use vi as an IDE, but it felt awkward at best.
Now I'm just wondering, what are the typical use cases for vi? Is it typically used to edit small files, or can it be used for larger projects? And if you use it in larger projects, how do you make it work? Or would it be a lot easier to use an IDE with vi keybindings?
People use non-IDE editors like Vi(m) for coding due to the following reasons,
They are non-distractive, allows you to concentrate on the job.
They do not clutter you screen area, offers you more code space
They are faster
They have better/faster/cooler text manipulation at the stroke of the finger
You happen to move your hands out of the keyboard less to hold the mouse, drag it here and there and click.
They also have the flexibility to support other tools like debugger, document viewer, etc.
They also have ways to get things like code folding, etc.
For a normal programmer whose ideal work cycle is sit, write code, test, debug, more code, test debug.. Vi offers a simplistic yet powerful environment to get the work done faster and more efficiently.
For someone who had years of using some IDE, it might be like using some prehistoric tool, but once they have been through the initial days, then there is no looking back. They'd feel like there is no better thing.
Why, oh WHY, do those #?#! nutheads use vi?
I've haven't done anything that you'd call a big project in python (only little test scripts), but I use Vim exclusively for writing large embedded C applications and I have never really felt the need for an IDE.
Vim is fast to start up, extremely fast to use and (with a bit of customisation) can do most things that an IDE can do. It'll do code completion, code auto-indentation and reformatting and it is very good at refactoring. The project plugin http://www.vim.org/scripts/script.php?script_id=69 makes it very easy to manage projects with lots of files and the taglist plugin http://www.vim.org/scripts/script.php?script_id=273 is great for browsing source code. It also allows you to have the C code open side-by-side with python code, assembly code and latex documentation without having to use a different tool for each.
Overall though, I think there is one really valuable thing that Vim gives you that very few other editors do and I would find it very hard to lose that: I can have a window split into three parts like this:
Each of the subwindows can either show a separate file or (as in the screenshot) a separate part of the file. I imagine emacs can do this (although I could be wrong), but I doubt many IDEs can. This can be invaluable for refactoring and for referring to other parts of the file.
I've used VI(M) and Emacs as my primary editors for years... I've tried switching to IDEs but find they can't get out of my way enough. I always end up back in VI(M) or Emacs after a while. One major reason is that I find my hands need to leave the keyboard too much in IDEs as they require the mouse too often... And I'm too lazy to setup my own shortcuts for everything.
Here's why I use it.
it's fast to start up
it's available across multiple platforms and is on all Unix machines
it's fast to use (keystrokes for common operations, operations based around words/paragraphs etc.)
However, I use IDEs for large scale development work, since I can't believe they can be beaten for productivity, given their code-awareness and refactoring capability. I use Eclipse, but I plug a VI editor emulator into it. See this answer for more details.
I saw some tutorials on how to use VI as an IDE, but it felt awkward at best.
There's one thing to do at the very beginning: throw your sense of aesthetics overboard. You will never get the same kind of graphical experience in VIM as you do in a decent IDE.
That said, VIM actually does offer many of the features of a full-blown IDE and has a lot of advantages besides. I use VIM for almost all of my developing work and all of my text documents (using Vim-LaTeX) – even though I've actually paid money for Apple’s office suite, iWorks.
There's one point that's still nagging me, though: I can't get IntelliSense to work. For me, that's a huge problem, especially when using languages such as VB, C# or Java, for which excellent IDE support exists.
So, the learning curve for VIM is steep but once you've passed a certain point it's everything but awkward. In fact, compared to VIM's editing experience, you will find that it's the IDEs that suddenly feel awkward because while they're good at bookkeeping stuff, they suck at editing.
I frequently work on a remote system, programming for a cluster, or editing config files on a headless box. All of these could be done with a file transfer, a regular IDE, and another file transfer, but it is so much faster to just use VIM through SSH.
You can find it (or easily install it) almost anywhere - Runs on all systems that can implement the standard C library, including UNIX, Linux, DOS, Windows, Mac, BeOS, and POSIX-compliant systems.
The ability to log into a remote server and confidently edit a config file is priceless.
Vim is not very good at code awareness. What it is good at is text manipulation. It provides you with the tools for you to edit text, not to edit for you. If you just do "small" edits and don't read up on the occasional "vim commands you wish you knew" you'll never understand the power provided.
code formatting
Formatting is done with =. You can also point equalprg to an external program to do the formatting for you.
import organizing
Vim won't be able to remove unused imports but if you select the import lines
:'<,'>sort
simple overview over all packages
:vs .
This will open a vertical window containing the current working directory :)
In conclusion, vim can't replace your IDE but it will let you edit your text.
As usuall: Choose your tool depending on the work you have to do! ;-) I'm using Vim and Visual Studio. You don't have to choose only one.
If you need an IDE, use an IDE. Vim is made for text manipulation.
It supports any languages. Try to edit a Ruby script with Visual Studio.
Performance on large files is much better than for most IDEs. Try to analyze a logfile having 100k lines and more using your IDE.
It runs on many plattforms and you can use it via a remote console, if you have to edit files on a server.
...
IDEs are specialized tools, which are good for problems they are made for. Vim is an incredible flexible and powerfull generall purpose tool.
This is obviously a hot topic so I'm going to give a list of reasons why I prefer IDE editor for coding.
1) I prefer to be able to fold sections of my code (I don't know whether Vi(m) can) without having to remember the command to do so or type it.
2) I prefer one click compile button/command as opposed to having to remember my compile command and it's library of options
3) I prefer the easier highlight copy paste operations without having to........ aah sod it!!
Well by now you get the picture. I'm not knocking Vi(m) I just think having your the elements and functionality of your coding environment visually represented makes for a clearer head and encourages exploration of options you may not know exists.
I much prefer vim over vi and prefer not to lump them together. Vim provides some features that are really handy and not always immediately obvious. Already mentioned was screen splitting. Also you may want to checkout ctags or exctags. These allow you to jump around the code base from within vim. I can place the cursor over a called method, jump to the definition, jump to a definition within that method, etc. Very powerful for tracing down bugs. Cscope is another similar program.
Vim will also allow you to run arbitrary shell commands within the environment and has powerful search and replacement features.
So an IDE will provide most of those, what will vim provide over a traditional GUI based IDE? That's easy, it runs on the CLI.
This allows me to login to my dev box, run screen (definitely something to checkout for the unfamiliar: http://www.gnu.org/software/screen/) and run multiple vim sessions within my screen session on my dev box. Now when I leave work for the day, I can leave my work session just as I left it, even while running builds. When I come into work the next day I can connect from my environment as if I never left.
Another reason to like vim or vi in particular, is that it can be found on virtually any Unix environment.
I am a quite happy user of Eclipse (I mostly develop in PHP and Python), however I found the answers to "What specific productivity gains does Vim/Emacs provide over GUI text editors?" interesting enough to make me wish to try out Vim or Emacs as well and see if they would turn out to be a better solution for me.
I have the general feeling that Vim and Emacs are not the kind of editor you learn by "playing with it" though. I have the impression you must dedicate some time and effort to "study" them a bit, before you can benefit from their power.
So, I have two questions for the community:
In the linked thread responders have essentially answered by commenting on Vim (often mentioning: "I'm sure Emacs has the same"). Google trends seems to indicate Vim is the mostly adopted between the two, however my first question is: knowing that I have no prior experience whatsoever on any of the two, and that I use and develop (mostly PHP and Python) on GNU/Linux systems (Ubuntu, Arch Linux), is there any of the two which would represent a better option to start with? (To be clear: my question is not about the quality of the editors but it is about what it is strategically better to learn in my situation).
What advice would you give me on how to learn using it/them? I know this is a broad question, but it is deliberately so. Have a look at this answer (unrelated topic) for an idea of the kind of information / style of answer I am looking for [but do not feel obliged to answer that way... any contribution will be welcome, in any form!]
EDIT (on picking the "accepted answer")
I picked one answer as the accepted one just now, but I would like to say "thank you" to all those who shared their experience and advice: almost all of it has being useful to me in some way. The thread has definitively exceeded my expectations! Thank you! :)
I would advise that checking out both is worth the time because of various reasons already covered by other answers or "Emacs vs vim vs XY" threads.
Still if you would have to pick one of them I'd go with vim because of one thing:
Availability
Vi(m) has the advantage that it is installed (not only available) by default on almost any *nix system. So no matter whether it is your system or someone else's or whether you are allowed to make changes to it or not, your favorite text editor and friend is there waiting for you.
Once you know vi(m) it feels awesome in those situations where you ssh into a machine and need to do something with text (navigating through a file, editing, whatever). You are going to feel like a King. I remember several times when I almost freaked out because nano or pico were not installed and I had to use "this ugly beast vi" which made unpredictable things when I started typing (because I wasn't in insert mode and didn't even know what that was) and when I was happy to have googled that ":wq!" gets me back out of hell. Now I can look back and smile about it.
I have the general feeling that vim
and emacs are not the kind of editor
you learn by "playing with it" though
Vim and Emacs are certainly editors that you "learn by doing".
Of course the question cries for including these highly scientific text editor learning curve graphs =)
Vim might be a bit harder in the beginning because its modal editing can feel quite unfamiliar at first. I think motivation is the key here. The article "Why, oh WHY, do those #?#! nutheads use vi?" explains the advantages quite well I think. In my opinion it really is worth to give it a try even while the learning curve might be steeper than with other editors and it sounds like you bring the necessary motivation.
Back to learning by doing.
Something I wish I would have done the first time:
Check out Vimtutor. It is an interactive tutorial which demonstrates the power of vim by showcasing it's basic commands and how they can be composed. Just type vimtutor in your terminal.
This helped me to really "get it" after trying to learn editing with vim several times in the past. The tutorial eases the learning curve dramatically as it explains the commands and makes you actually perform them so they become a habit. It really makes a difference compared to being frustrated because of feeling handicapped. Using vimtutor you also will see what the benefits of modal editing are and instead of fighting or ignoring it you are going to embrace it because you have experienced the advantages at first hand. I guess it would be pretty difficult to learn that all by oneself. So these 30 minutes are quite worth it.
I have the general feeling that vim and emacs are not the kind of editor you learn by "playing with it" though.
My experience with emacs is actually quite the opposite. I tried going through the tutorial, but it didn't seem to help much. The way I ultimately ended up learning is with a reference card and just forced myself to use emacs on my code until I got it correct*. Then again, I do also have a screw loose. Your milage may vary. Offer void where prohibited. You get the idea.
One other piece of advice I recall reading somewhere is to try writing down a list of about 10 commands you want to learn and keep it by you while coding. Once you've mastered those commands, make another list of 10 more. Keep doing this until you've got a big enough chunk of the editor committed to memory.
*Note that the linked reference card is out-of-date. If you google, you can get a more up-to-date reference card.
knowing that I have no prior
experience whatsoever on any of the
two, and that I use and develop
(mostly PHP and Python) on GNU/linux
systems (ubuntu, archlinux), is there
any of the two which would represent a
better option to start with?
I'm an emacs guy, so my opinion should be obvious. That said, you're likely best trying out the one that more people you know seem to use. Having someone who's experienced with emacs (and I'd assume vim) is a great help.
If you don't know anyone who uses either one, choose whichever one you feel is the prettiest or has the coolest name. You won't know enough to know which one you'll like, so you might as well choose arbitrarily.
For vim try vimtutor
I came to Vim when I started using Linux after years of Windows development, and had to do a lot of work on remote systems via ssh. For the first couple of weeks hated it. After that I could not live without it.
Probably the best way to start is to use Vim in easy mode ([g]vim -y), most installations have a shortcut called evim. This runs vim in a mode that is in insert mode by default and remaps keys to the usual Windows ones (ctrl-S to save, ctrl-X to cut etc). You can then use it like a regular Windowsy editor but still access the power of Vim.
There is also Cream which is Vim + a bunch of scripts to make it behave even more like a Windows editor.
I started out using evim and Cream, but found I gradually transitioned to using 100% vim.
Also if you use gvim then most of the functionality is also available through the menus and you can see the keystrokes for the same functionality.
Also read the docs - there are extensive help files available on every aspect. I still browse them from time to time and find something new.
Using VIM, I find the following quick reference card very helpful, especially for the stuff I don't do everyday:
VIM QuickReference
For emacs, you should read the GNU Emacs Manual. Don't try to do everything all at once.
Start with the basic stuff, and then move on to the more powerful features once you're comfortable with the easier stuff.
Some time ago I decided to learn vim beside Eclipse as well because of its powerful textual editing, search and navigation features. But - at the same time - I liked the project handling, code completion, refactoring and debugging features of Eclipse and I did not want to lose them.
Nowadays I use an Eclipse plugin called vrapper which provides me nearly all basic features of vim inside Eclipse without losing any Eclipse functionality. Of course it is not a full-featured vim but it gave me the productivity gain I 'expected' (motions, the dot operator, registers and marks). Also, this plugin can be considered the 'trial' version of vim where you can learn all basic and some advanced stuff within your 'best-known' environment.
There is another interesting approach called eclim. Eclim integrates Eclipse with vim from the vim side so you can use many features from Eclipse within vim.
For learning the basics of vim, this graphical cheatsheet helped me a lot.
I would go for Emacs.
Explicit command name will makes your task easier.
I switched to emacs after I had years of experience with vi and never looked back.
Go with tutorial first.
Hang out at #emacs in irc and people are happy to help you in real time, for whatever more you need.
My advice for learning emacs is to understand that everything is done by a command (written in elisp) that is connected (bound) to the key strokes that you make. The power of emacs comes from being able to write new commands and use commands that are not bound to keys (there are too many commands to bind each one to a command.) as well, of course, read and modify commands that are already in emacs.
Next learn how to use the Help key and how to make a key binding list, then how to search for relevant commands (apropos) and see if they are bound already.
Be ready to take learning diversions into the emacs manual (Help, Read manual, Emacs manual).
One argument in favor of Vim if you know Python is that you can write Vim scripts in Python. See :h python. Emacs requires you to learn elisp.
I find myself gravitating toward Vim for scripting languages like Ruby/Perl/Python/PHP, and for Emacs for languages that are more interactive (Lisp, essentially). If you develop your Python code using an interactive Python shell a lot, Emacs might be good, because you can embed a Python shell right into Emacs. If you write code and run it from commandline a lot, Vim can handle that easily enough via :make or :!.
I really recommend you learn both and pick whichever you like better. They are both worth knowing.
Wow, vi/vim vs emacs, what a temptation...
From a vi-user's perspective...
Always Therevi is on about every unix system ever released, in the default install, and available for Win
May save you from RSIvi uses home-row keys for just about everything, modifiers like control and meta are used only for rarely invoked functions and even shift-key use is moderate. This was probably all just a lucky accident, but don't laugh at RSI. It can happen to anyone, it's seriously painful, it's potentially career-ending, and it's hard to treat.
Starts up instantly.In the past, this was a huge advantage over emacs. Emacs users had to start up just once, and navigate everywhere within emacs. Today it starts faster, but in vi, it's perfectly reasonable to quit out of it entirely on every compile or test cycle.
Has an awesome line-mode The line mode in vi is backwards compatible to the original Unix ed(1) program, an editor that had only a line mode. That is, vi's regular-expression-substitution-engine-/-line-editor was once an editor all by itself.
Easily scriptableGot something you want to do to every .whatever file in your project? It's easy to write a declarative script that will edit a sequence of files. No need for imperative or procedural programming.
Easily extensibleVim, at least, can be extended in Python.
First of all, be humble.
As long as you remain aware that they are very powerful tools you'll be ok. If you are finding a task very difficult, and you are thinking 'it's just me that sucks not the editor', you're in the right mind to learn and improve.
Bram's 7 habits are a good tenets to go by
http://www.moolenaar.net/habits.html
Also I highly recommend having a go at writing a plugin. It doesn't matter what it does. It gives you the impetus to dive deep into the manuals.
Maybe, a good way is to learn vim/emacs while using eclipse. Try vimplugin or emacsplus plugins for eclipse.
This should really just be a comment, but against which answer ...
With Vim I'd suggest using the GUI version for a start, just dive in, the built-in help is excellent (:h and the screen splits adding a panel with comprehensive "hyperlinked" help pages). With vim the only potentially dangerous operation is a write, everything else you do is recoverable per command or edit (undo & redo).
The power acquired easily incentivises the learning.
Here's the way you learn: Start typing. When you hit a point where you want to do something other than typing, look up how you do that. Repeat. It helps to start with a few basics, say 7 fundamental commands. Other than that, when you run into wanting to do some operation, look it up and use it.
This great Tutorial was a big help for me for my first steps in Vim. It is a gently introduction and explain at the same time the philosophy of vim in a pleasant way:
aByteOfVim
The way I learned emacs was mostly by doing both of the following:
All the GUI menus show you the key-bindings you can use to execute the same command as that menu item. Pay attention to the bindings for the menu items you select a lot, and try them out manually next time you get a chance.
ctrl-h ctrl-h (think "Help! Help!") brings up a buffer that shows the various types of help available. If you then hit the "b" key (the buffer calls it "describe-bindings"), you will get a list of all the key bindings that are available in the buffer you are working on. Just peruse that every now and then with an eye for commands that look useful. Try them out when you get a chance.
As for vi, I learned it in the days before vim, so I pretty much had to use man vi to figure it out. Most of us emacs users will tell you that all the vi you need to know is :q! ("quit, and I really mean it"). :-)
But in truth if you are a Unix user you need to learn at least enough vi to do simple edits to config files and save them. You never know exactly what (if anything) you will get when you try to start emacs on a strange system Unix system, but vi is always there.
Nearly everything you see or interact with in Emacs can tell you about itself -- you just need to know how to ask it.
To learn Emacs, learn about the current Emacs context: what the values of things are, what the relations between them are, how they are denoted, how you can change them or otherwise interact with them.
The most important thing to learn is that Emacs is Emacs Lisp -- it is a Lisp ecosystem. Learning Emacs means also learning Emacs Lisp -- the more you know, the better. Lisp is the most flexible and most powerful way in which Emacs realizes itself as "the self-documenting, extensible editor".
Icicles can help you learn Emacs and Emacs Lisp. It helps you ask Emacs about itself. This page gives an overview of the ways it does that: Emacs Newbie with Icicles.
Don't get caught up in the vi(m) versus emacs religious war. They are both great editors. I originally started with VI (real VI not VIM) and later started using Emacs. These days, I tend to use both, but emacs more because emacs has some features I need which are not in vim.
The real challenge and what you should be aiming for is how to be as efficient, quick and accurate as possible with your editor of choice. Both VI and Emacs have a lot to offer in this respect. However, much of it boils down to two main habits you need to develop
Don't use the mouse. Both editors were created when mice were not the plague they are now. When it comes to editing, cutting, pasting, highlighting etc, both editors offer keyboard equivalents. Use them and keep your fingers on the keyboard. You will be surprised how much faster you will become
Avoid the arrow keys. This is for a similar reason. The arrow keys tend to make you move your hands off the main keyboard. In the end, this also slows you down and makes you less efficient. Both editors provide far more convenient functions which are faster.
These are the two main things to focus on when learning either of these editors. There is lots more, but to start with, just start with focusing on using the main keyboard.
After you have got that down pat, then begin to think about how you can tweak your environment to suit your needs. By this time, you will be familiar with the power of the editor you have chosen and will probably have some ideas. Both of these editors are very configurable. I find emacs is the most configurable, but you can easily get lost iin writing elisp to configure things and before you know it, your an elisp programmer who does a bit of PHP and Python. To some extent, the same can happen with VIM, but to a lesser degree. However, note that the defaults have usually been set by people with lots of experience and who probably know something you don't. Avoid making the mistake of trying to modify either editor to be what your use to. Learn how it works with minimal config first and then change once you have an idea of why it was done some way - know the rules before breaking them.
If your serious about programming, your editor will be your most important tool. Other important tools are your screen, your chair and your keyboard. The rest is incidental.