I have a file with several lines of scala code -- imports, list value assignments, etc. that I often use to initialize some things when using the REPL.
Currently I just open up the file in a text editor and copy-and-paste it into the REPL, but is there a way to do it by calling the external file in a more direct manner so I don't have to copy-and-paste every time?
In some interactive database tools like SQL Plus, it is done by typing #filename at the prompt. Is there something similar in the Scala REPL? Preceding the filename with # doesn't work, eval doesn't work either.
Type:
:help
and you see, that
:load <path> load and interpret a Scala file
solves your problem.
In some circumstances, pasting the code might be preferable though, but then
:paste
might be your friend then. It helps inserting a whole block without feedback, line by line, until you hit Ctrl + D. In some cases this is significant for the code interpretation.
Related
I have an .ml file and I want to be able to run it line-by-line as if I was typing it in the top-level ocaml interpreter
The problem is, if I simply type "ocaml file.ml" in the terminal, I don't get the output from the REPL, and I can't debug and compile it, since it contains the #use directive.
I've tried using several different extensions for Visual Code, but none of them worked for me.
Is there anything I can do to simply be able to run the file and get the output from the ocaml REPL?
Thanks.
I never used VS Code (if you are referring it as 'Visual Code'), but SLIME in emacs or its Vim version of it is probably what you want.
Based on that, I tried searching for an VS Code extension that does works like SLIME: SendToREPL.
(Disclaimer: the author claims it works for Python, Node, and reply (not sure what it is though), but I am quite confident that it will work for OCaml REPL/UTop.)
I've recently set up Portacle 1.3 for learning common lisp on Win 7. However, whenever I run my code I get the error, even if there is no code.
Running individual lines works fine, however. The error only shows when I run the whole file.
I tried putting some code in an EVAL function, but I believe that only accepts one argument at a time, so I couldn't run a whole program in it.
I've found a similar error in this stackoverflow page, but their code contains colons and that's where their error lies.
I think it might be an error in the code that runs mine, seeing as I get the error even if I compile with no code, however I know nothing.
The full error:
main.lisp:1:1:
read-error:
READ error during COMPILE-FILE:
illegal terminating character after a colon: #\
Line: 1, Column: 13, File-Position: 12
Stream: #<SB-INT:FORM-TRACKING-STREAM for "file [path to file]\\main.lisp" {1005F5F0D3}>
Compilation failed.
Portacle is a standalone Emacs packaged with everything needed for Common Lisp development and which uses SBCL as the Common Lisp implementation.
I believe what you do when you say 'compile the whole file' is call slime-compile-and-load-file which is bound to the key sequence C-c C-k by default. There are a lot of moving components here:
Emacs is the text editor here. It also takes care of launching all the necessary components for Common Lisp development.
Slime is one such component. It serves as interface between Emacs and your Common Lisp implementation (SBCL in this case, but supports any Lisp in theory). Basically it sends the code you wrote in Emacs to your Lisp for evaluation.
SBCL is the Common Lisp implementation. In this case it is a compiler. This is what evaluates the code it receives and spews out the answers to the user interface in Emacs, through Slime. It also 'lives', in the sense that you interact with it by modifying the state of the loaded Lisp image, keeping track of defined functions, global dynamic variables and much more. This is why you can have the REPL, and why you need Slime to interact with it.
So to debug your problem, I would try to:
Launch SBCL from the Windows shell and run a simple .lisp file to check that everything works. You can put for example (format t "~a" (lisp-implementation-type)) in a .lisp file and run it in SBCL from the shell by calling (load "...\\file.lisp"). It should return "SBCL".
Create a completely new file using Emacs (and not weird Windows programs that could mess up the files) (C-x C-f), and try to call the compile from there (C-c C-k).
And I believe you made the right choice of IDE. Portacle is arguably the simplest tool out there if you are a total beginner in Common Lisp and do not know Emacs configuration. The keybindings are a bit daunting though.
I'm trying to have my Vim setup automatically fold import statements when I open a Scala file. This is similar to what Intellij does when you open a file. I currently have the following lines in my .vimrc file from the wiki.
set foldmethod=syntax
set foldenable
syn region foldImports start=/(^\s*^import\) .\+/ end=/^\s*$/ transparent fold keepend
However when I open a .scala file it doesn't fold the imports but the body of objects. I am also using the vim-scala plugin. Thanks for the help!
You were pretty close to getting this to work. There are a few funky factors at play that we should consider.
setting foldmethod to syntax (btw this is not documented on learn Vimscript the Hardway..so :help foldmethod was key to figure this out)
SYNTAX fold-syntax
A fold is defined by syntax items that have the "fold" argument.
|:syn-fold|
The fold level is defined by nesting folds. The nesting of folds is
limited with 'foldnestmax'.
Be careful to specify proper syntax syncing. If this is not done
right, folds may differ from the displayed highlighting. This is
especially relevant when using patterns that match more than one line.
In case of doubt, try using brute-force syncing:
:syn sync fromstart
The main thing to note is the sync fromstart this is a useful helper if you have regex that would match throughout the file and only want to catch the header. In your case you should be able to ignore this but just something to be aware of.
top down regex scanning
Since the import block is fairly predictable we can simplify the start and end to look something like this:
syn region foldImports start="import" end=/import.*\n^$/ fold keepend
Since the region is just looking for some string to start the matching on we can just use "import"(or /import/) and then for the end value we want to use a little bit more carefully crafted statement. The key is that we want have the end be the last line of the import with a blank line following it (/import.*\n^$/)
Hopefully that does the trick for you (I do not work with scala so you may have to adjust the regex a bit as needed)
Simple question here, just can't seem to pass it google in a way it can understand.
Say I wanted to execute a line of actual programming code (c++ or java or python... etc) like SetCursorPos or printf from the command prompt command line. I vaguely imagine I would have to invoke the compiler and pass the command to it like a parameter, where from it would then be converted into machine language and passed to... where exactly?
Okay so that was kind of two questions.
How to run actual code from the command line and
what exactly is happening when a fully compiled program, or converted line of code (presuming these are essentially binary containers at that point), is executed?
Question one takes priority obviously. Unfortunately, I can not find any documentation on it, just a bunch of stuff vaguely related to it.
How to run actual code from the command line
Without delving into the vast amounts of blurriness between them, there are two major categories of language implementations: interpreters and compilers.
With many interpreters (or implementations with implicit compilation, such as V8 JavaScript's jit compiler, or pretty much anything with a repl), running a single line from the command line should be fairly trivial. CPython (the standard implementation of Python) has the -c command option:
$ python -c 'print("Hello, world!")'
Hello, world!
Language implementations with explicit compilation steps will tend to be decidedly less simple. In particular, the compiler would need to either accept source either from directly out of the argument list, or from standard input (via piping or redirection). On the output side, your compiler would have to support immediately executing that program, or outputting it to standard out, so that an operating system feature (if it exists) can execute it from a pipe.
To my knowledge, most explicit compilers are not designed with such usage in mind. In such cases, your best bet is to see if there is a REPL available for the language in question, preferably one as compatible with your compiler as possible, or to create (or find) a wrapper that makes it look like your language has a REPL. The wrapper would:
Accept input along the lines of CPython above.
Create a temporary source file behind the scenes with the code to be run and any necessary boilerplate.
Pass that file to the compiler.
Automatically run the resulting executable.
Delete the source file and executable. These may be cleaned up by the operating system later instead, if they're in a temp directory.
From the point of view of the user, this should look pretty similar to the CPython example, as they wouldn't have to interact with or see the compiler or temporary files.
I frequently use the Scala console to evaluate and test code before I actually write it down in my project. If I want to know the contents of a variable, I can just enter it and scala evaluates it. But is there also a way to show the code of methods I entered?
I know there's the UP-key to show single lines, but what I was searching for is to show the whole code at once.
There's a file in your home directory named .scala_history that contains all of your recent REPL history. I regularly copy and paste code from this file into project source files. It's not exactly the same as showing the code for individual methods in the REPL, but it might help you accomplish the same goals.
See the comments by Paul Phillips in this issue for a discussion of some related functionality in the REPL (grouping statements in the history):
At some point I implemented the logic for this, but the real obstacle
is jline. It has enough trouble figuring out where the cursor is under
the simplest conditions. Start throwing big multiline blocks into the
history and it breaks down in tears. Would love to see this and
SI-2547 addressed by the community.
...
I expect to fix this soon too, but it depends on how well the recent
jline work goes. I implemented it long ago, and display issues are the
impediment.
Both of these comments are over two years old, so I wouldn't hold your breath.
I dont know a command to load all the code from command line.
What you can do is to :load path/to/my/file.scala to load some complex code and re- :load it when you changed the code in the file.