Is there anyway to check the terminal (Linux, and Windows) for characters at certain positions? I have external methods loaded via an explicitly loaded dll that prints certain characters onto the screen. I need to see if the functions printed what they were supposed to with minimal cross talk between the between the plugins. So at the core I am wondering if C++ has any feature for pulling chars off of the termial/command line?
This is not possible on VT100-like terminals (the kind popular in Linux.)
For Windows I can't say, but if you are using a cygwin terminal (not the power shell or the "DOS shell") the answer is again no.
You could use tmux or screen to set up a virtual terminal. The display state can then be captured, which seems to be what you want. But something in my brain is telling me that, whatever you are trying to do, this is probably not the right solution. What exactly is your problem?
After defining variables, functions, etc., can you save what you have done on the REPL too an text .clj file?
most people work with the repl through an editor such ad Eclipse/Emacs/vim and that editor has the ability to save the repl, though without some diligence on the developers part this will likely be an incomplete record of what happened. Some of the state of the repl may have come from loading files etc which will be in a different state.
So the short answer is typically not.
In Linux (mine = Ubuntu 16.04.2 LTS) if you are using lein then check for .lein (hidden directory) and look for repl-history. You should find the commands that you have typed or pasted into the REPL. This can be a source for later edit - I use geany...
I am answering the parenthetical part of your question. For me, the Clojure REPL is very useful for testing functions and proving out concepts that take no more than a few lines. I will often put hooks in a module that is not the main, just so I can load a file and run it through a couple of functions. I can also do this from main using the same mindset; that is write a debug function.
I found the Eclipse plugin to be quite useful, but I do not use it much these days, mostly Vim and running the module with one or more special functions and running the main. I don't know of any way to save REPL state.
So I have been working on a Clojure tutorial and it's pretty fun so far. Unfortunately, every time I close my REPL out, I lose all of the defn and def that I created in the previous session.
So, to save time in the future, is it possible to have the Clojure REPL save everything I've typed to a file so I can dig out what I need for future uses?
I think most people work by using their IDE to send fragments of code to the REPL, rather than doing a lot of direct hacking in the REPL. This way you have a better idea of the current state of the program.
If you use Emacs and SLIME, you can save the REPL buffer to a file just like saving any other buffer.
If you are using a Unix-like operating system you can start your REPL using rlwrap. This would give you Ctrl-R for accessing commands from history in an easy way, as well as storing the history itself.
You'd just have to install rlwrap and prepend it to the line where you start REPL, e.g. rlwrap lein repl
Couple of tips:
I do a lot of coding in the REPL, but as soon as I write something that works then I copy/paste it into a source file. Then I can just run or reload that source file whenever I want to get a REPL environment back to a fully configured state.
Some REPLs (e.g. the Eclipse Counterclockwise REPL that I use) keep history from previous sessions so you can up-arrow to the earlier REPL commands you want to repeat.
This is actually a harder problem than it seems because a dump like this must take into account symbol and vars dependencies and output to file in the correct order of symbols. That said since code is data one should be able to write a function that does that.
I'm having some trouble using SML/NJ interactive system, namely, that when I try to use my arrow keys (either left or right to make a correction in the expression I've typed, up to repeat the last expression), my Terminal prints codes. (e.g. ^[[A for up^[[D for left, etc.). While I can still use the system, it makes it very tedious.
I've looked around in Control.Compiler, is there something I'm missing? For whatever its worth, I'm using the Mac Terminal.
Thanks ^_^
Another option is rlwrap.
rlwrap sml
Try this. You can use socat to add readline support to many things:
socat READLINE EXEC:sml
I just realized you're on OS X. socat does seem to be available for OS X, although I have not tested it (this does work on Linux).
Clojure has introduced me to the concept of Lisp syntax, and I'm interested, but it's a pain to get the Clojure repl set up and use it on different machines. What other resources are there out there for actually on-the-fly testing and playing with Lisp syntax?
I'm imagining something like a website where you can input rudimentary code, or a browser add-on, or even just a standalone application that steps you through Lisp (something that runs on Linux/Ubuntu).
Haven't been able to find anything like that to start me off in a simple/accessible way.
The SISC Online REPL is exactly what you need. It accepts Scheme syntax, which is a variant of Lisp.
For a standalone app I like PLT Scheme because it seems to work the same on every platform I've tried. I was previously using MIT Scheme on Ubuntu, but decided to switch when I bought a new machine with 64-bit Vista installed.
At the risk of losing all of my rep points, try newlisp.
I've used LispBox in the past. Easy to set up and get going, but I have to admit that Emacs is second nature to me. If you're unfamiliar with that, you may can use another editor, but getting intimate with Emacs will help you live comfortably in Lispville.
It's not hard to get to a Clojure REPL nowadays.
Go to http://build.clojure.org/ and download clojure.jar.
Install a JVM.
java -jar clojure.jar
This should work on any machine that has a JVM installed.
For more fun, install rlwrap and use rlwrap java -jar clojure.
For learning Lisp the LispWorks personal edition is fine: LispWorks downloads. There are versions for Mac OS X, Windows, Linux and FreeBSD. All have the same user interface capabilities and this includes an editor and listener - plus lots of other tools. On Linux and FreeBSD in currently (LispWorks 5) uses X11/Motif for the GUI - this will change in a future version (LispWorks 6) to GTK. So to run it now under Linux, you need to have the Motif lib installed. Other than that using it is relatively painless. There are some restrictions to it (only 5 hours runtime, then you need to save and restart, ...) and the full version is commercial. But for learning some Lisp basics, it is quite good.
Franz has an online REPL for Allegro Common Lisp.
http://www.franz.com/products/allegrocl/prompt/
codepad.org is a nice simple online way to enter and run code (in many different languages, including Scheme). I use it all the time for testing out snippets of code to use in SO answers.
I won't edit Lisp code without an editor that does what Emacs will do with the following configuration:
(define-key lisp-mode-shared-map "[" 'insert-parentheses)
(define-key lisp-mode-shared-map "]" 'move-past-close-and-reindent)
The former inserts balanced parentheses. If you give it a numeric prefix argument, it inserts that many nested pairs. By default, it inserts one. If you have a text region marked, it encloses that region in the innermost inserted pair. That means that you'll never open a parenthesis that's not closed.
The latter is harder to explain, as it's used less frequently. It's more of a navigation command than an insertion command. It confirms that you're done editing the current form and moves the cursor up, out, and past it, preparing for the next likely insertion.
With these keys bound, one no longer needs to use the Shift key to access the parentheses. Also, this leaves the parentheses keys bound as normal, for when sexp repair or a literal parenthesis character is required. I stole the bracket keys because they're used so infrequently in Emacs Lisp and Common Lisp. The bracket characters are still accessible with meta key bindings:
(defmacro make-key-inserter (def)
"Substitute for `self-insert-command'."
`(lambda (arg)
(interactive "*P")
(insert-char ,def (prefix-numeric-value arg))))
(define-key lisp-mode-shared-map "\M-[" (make-key-inserter ?\[))
(define-key lisp-mode-shared-map "\M-]" (make-key-inserter ?\]))
It's not essential to use Emacs, but don't settle for less with another editor that can't at least match this capability. There's also a whole family of commands for navigating and manipulating the sexp tree as a tree. Understanding why that's valuable will require you to fumble around for a while until you stop seeing syntax and start seeing the tree.
Since you're using Ubuntu, I'd just install some of the packages and give them a try.
Common Lisp: apt-get install clisp
Scheme: apt-get install drscheme
These aren't the only packaged implementations, but maybe the easier to get started with. You'll be able to play at a REPL and also run your own scripts through the interpreter.
BioBike provides a full Common Lisp evaluator through the web (with extras like a knowledge representation system, biocomputing, and an alternative visual langauge as well).
If you just want to play with LISP, interactively, quickly, GNU Emacs has a LISP interpreter built in, and listening in the *scratch* buffer. Type an S-expression, position immediately after it, and then hit Ctrl-J to evaluate it. Or <ESC>: will put an Eval: prompt in the minibuffer, accept an S-expression, and evaluate it.
You can define functions, using defun, and test things that way. You have access to ALL of the GNU Emacs built-in functions, and anything you have loaded. If you want to keep things around, you can put them in your .emacs file.
https://github.com/fogus/himera
was very easy for me to setup on a https://www.nitrous.io virtual box. Makes a nice web interface.
Downloading and running clojure-1.6.0.jar on my windows (XP) box was as easy as using this script to run the REPL :
java -cp clojure-1.6.0.jar clojure.main