I am using SML NJ v110.78 on Mac OS X 10.9. I am trying to use command-line arguments from BASH, like so:
sml progname.sml 2.0 1.0.
The program progname.sml compiles and runs and uses the command-line arguments to produce a value (using SMLofNJ.getArgs() function), but at the end of the processing, the REPL returns the error:
!* unable to process `2.0' (unknown extension `0')
!* unable to process `1.0' (unknown extension `0')
-
How do I avoid those final error messages?
Thank you.
You need to terminate the REPL with an exit statement:
val _ = OS.Process.exit(OS.Process.success);
When you don't exit the REPL in above manner then the command-line arguments are regarded by the interpreter as compiler extensions, hence the feedback:
!* unable to process `2.0' (unknown extension `0')
BTW: You can use OS.Process.exit(OS.Process.success); to exit the REPL as a cleaner alternative to CTRL+Z
How do I quit SML?
ML Command Line Options Cheat Sheet
Related
This question has been asked before, but I have tried the solutions in related questions such as this to no avail.
I am having problems with Python's exit command, and I have ruled out a problem with my code as run by vanilla Python 3. The problem comes when I run it with iPython or in Spyder's iPython console.
When I use just a simple exit command, I get the error:
NameError: name 'exit' is not defined
I have already imported sys as suggested by the other link. The only thing that kind of works is to try sys.exit() in which case I get:
An exception has occurred, use %tb to see the full traceback.
SystemExit
C:\Users\sdewey\AppData\Local\Continuum\Anaconda3\lib\site-
packages\IPython\core\interactiveshell.py:2870: UserWarning: To exit: use
'exit', 'quit', or Ctrl-D.
warn("To exit: use 'exit', 'quit', or Ctrl-D.", stacklevel=1)
I only say that that "kind of works" because the error message is smaller so it's less annoying :).
Any ideas? Seems like an issue with iPython. I have encountered a different issue in Jupyter (which uses iPython) where quit was ignored entirely, which I posted about separately here
I've run into the same issue while running scripts containing exit() in Pycharm's IPython shell.
I learned here, that exit is intended for interactive shells, so behaviour will vary depending on how the shell implements it.
I could figure out a solution which would...
not kill the kernel on exit
not display a traceback
not force you to entrench code with try/excepts
work with or without IPython, without changes in code
Just import 'exit' from the code beneath into scripts you also intend to run with IPython and calling 'exit()' should work. You can use it in jupyter as well (instead of quit, which is just another name for exit), where it doesn't exit quite as silent as in the IPython shell, by letting you know that...
An exception has occurred, use %tb to see the full traceback.
IpyExit
"""
# ipython_exit.py
Allows exit() to work if script is invoked with IPython without
raising NameError Exception. Keeps kernel alive.
Use: import variable 'exit' in target script with 'from ipython_exit import exit'
"""
import sys
from io import StringIO
from IPython import get_ipython
class IpyExit(SystemExit):
"""Exit Exception for IPython.
Exception temporarily redirects stderr to buffer.
"""
def __init__(self):
# print("exiting") # optionally print some message to stdout, too
# ... or do other stuff before exit
sys.stderr = StringIO()
def __del__(self):
sys.stderr.close()
sys.stderr = sys.__stderr__ # restore from backup
def ipy_exit():
raise IpyExit
if get_ipython(): # ...run with IPython
exit = ipy_exit # rebind to custom exit
else:
exit = exit # just make exit importable
You can use system warnings to set those warning that you do not need as ignored. Example:
the function that you call from somewhere else:
def my_function:
statements
if (something happened that you want to exit):
import warnings
warnings.filterwarnings("ignore")
sys.exit('exiting...')
I want to quit swift repl gracefully and not use ctrl-d to exit it.
For eg. python repl can be exited by typing exit(). Is there a similar way of quitting swift repl?
This answer complements Ankit Goel's correct :quit answer to also (1) provide an understanding of why the : is needed and (2) other options besides :quit.
Swift REPL works in conjuction with the LLDB debugger.
: is a REPL escape prefix to execute an LLDB command. From within REPL, :help will list the available LLDB commands.
Any of the following will quit both Swift REPL and subsequently LLDB with a single command line.
:exit
:quit
:q
One can also exit REPL into LLDB with just : and, then later quit (or exit) using the LLDB command directly.
sh$ swift
Welcome…
1> print(18 + 4)
22
2> :
(lldb) print "hello"
(String) $R0 = "hello"
(lldb) quit
sh$
Addendum: The LLDB command c or continue can be used to return to the Swift REPL environment.
Just found out that a graceful way to quit swift repl is by using typing :quit
It does not work without the colon.
I decided my birthday would be a good time to try and fix my Lisp problems.
I've received a Lisp program from someone to run an experiment. It works well on his OS X environment. However, I can't get it to run on either Windows 7 or Ubuntu. The program uses Act-R 6.2 to run a model. When I try to load the .lisp file I receive the following error:
:Reader error on #<BASIC-FILE-CHARACTER-INPUT-STREAM ("*path*"/28 UTF-8)#xCFAD1AE, near position 1048, within "smile* (#initWithCo":
Undefined character #\/ in a #\# dispatch macro.
While executing: CCL:SIGNAL-READER-ERROR, in process listener(1)
The error is the exact same for Windows 7 and Ubuntu. Here is the console output if it is required:
http://i.stack.imgur.com/dFXVm.png
It seems load-turing-application.lisp loads multiple other files, one of which is turing-application-v1.lisp, in which the line (setf *smile* (#/initWithContentsOfFile: (#/alloc ns:ns-image)(ccl::%make-nsstring "smiley.jpg")))
seems to be the culprit. I suspect it has something to do with the #/-notation.
Any ideas would be appreciated.
This is answered in the comments, but #/ is a CCL syntax that only is available on OS X. This code is not expected to work on linux or windows.
Below lines when i put them in test.py and runs it, gives me error but runs fine when i run them from command line.
pyvar = 'Hello world'
!echo "A python variable: {pyvar}"
jitu#jitu-PC:~/ipython/python$ ipython test.py
File "/home/jitu/ipython/python/test.py", line 2
!echo "A python variable: {pyvar}"
^
SyntaxError: invalid syntax
Any idea why it is not working ?
.py file are python script, they are supposed to be pure python, IPython will not try to do some "magic" on it. You should rename your script to .ipy if you want to use the syntactic sugar IPython offers on top of pure python syntax.
Note that all IPython syntactic sugar can be transformed into pure python (cf %hist vs %hist -t) that will be valid python syntax, but still need to have access to an IPython instance.
I'm using the Scala REPL to interactively test some hash functions I'm building. I'm constantly switching between the product code (Eclipse), the browser and the Scala interpreter, doing copy/paste of values and results. In the mix I'm often doing CTRL-C on the interpreter, exiting the session and loosing all my functions.
Is there any way to let the Scala REPL either ignore CTRL-C or, even better, perform "paste" with it? I'm working on Linux.
I only know how to prevent REPL from exiting. Remapping of CTRL+C to perform copy command could be done in the same way (if there is some command that ables to change keymap w/out restarting terminal -- I don't know is there one). Anyways, to block ^C wrap your REPL invocation in .sh script like this:
#!/bin/bash
#switch off sensitivity to ^C
trap '' 2
# here goes REPL invoke
scala
#get back sensitivity to ^C
trap 2
trap command
defines and activates handlers to be run when the shell receives
signals
or other conditions.
2 is a SIGINT value (that's the signal which is triggered when you press CTRL+C)
The repl already intercepts ctrl-C, but apparently it doesn't work on linux. It does work on osx. If someone who uses linux opens a ticket with sufficient detail to indicate why not, I can fix it.
As an alternative to the native Scala REPL, you can use Ammonite, which does handle Ctrl+C:
# while(true) ()
... hangs ...
^Ctrl-C
Interrupted!
#
The traditional Scala REPL doesn't handle runaway code, and gives you no option but to kill the process, losing all your work.
Ammonite-REPL lets you interrupt the thread, stop the runaway-command and keep going.