I'm following along this thing: J Dictionary
It tells me to issue the command d by d over d!/d where d is a list, but my jqt environment tells me value error: over. If the problem is that I'm supposed to import/install/activate a library, I don't see any instructions in the documentation about that. Anyone know what's going on here?
From the documentation you linked:
The verbs over=:({.;}.)#":#, and by=:' '&;#,.#[,.] can be entered as utilities (for use rather than for immediate study)
It's telling you to define those verbs in order for the following code to work.
So they're not part of the standard library nor any other library - you're supposed to define them yourself.
Related
I need to open a .xlsx-file (without writing to it) in python, to change some fields and get the output after the formulas in some fields were calculated; I only know the input fields, the output field and the name of the sheet.
To write some code: Here is how it would look like if I would have created the library
file = excel.open("some_file.xlsx")
sheet = file[sheet_name]
for k, v in input_fields.items():
sheet[k] = v
file.do_calculations()
print(sheet[output_field])
Is there an easy way to do this? Wich library should I use to get the result of the formulas after providing new values for some fields?
Is there a better way than using something like pyoo, maybe something that doesn't require another application (a python library is clearly better) to be installed?
I'll just thank you in advance.
I now came up with a (very ugly) solution.
I am now reading the xml within the xlsx-file, and I am now using eval and some regular expressions to find out wich fields are needed; and I have defined some functions to run the calculations.
It works, but it would be great if there were a better solution.
If the resulting library is ready, and I don't forget to do this; I'll add a link to the library (that'll be hosted on Github) to this answer to my own question.
I'm currently trying to learn Nim (it's going slowly - can't devote much time to it). On the other hand, in the interests of getting some working code, I'd like to prototype out sections of a Nim app I'm working on in ruby.
Since mruby allows embedding a ruby subset in a C app, and since nim allows compiling arbitrary C code into functions, it feels like this should be relatively straightforward. Has anybody done this?
I'm particularly looking for ways of using Nim's funky macro features to break out into inline ruby code. I'm going to try myself, but I figure someone is bound to have tried it and /or come up with more elegant solutions than I can in my current state of learning :)
https://github.com/micklat/NimBorg
This is a project with a somewhat similar goal. It targets python and lua at the moment, but using the same techniques to interface with Ruby shouldn't be too hard.
There are several features in Nim that help in interfacing with a foreign language in a fluent way:
1) Calling Ruby from Nim using Nim's dot operators
These are a bit like method_missing in Ruby.
You can define a type like RubyValue in Nim, which will have dot operators that will translate any expression like foo.bar or foo.bar(baz) to the appropriate Ruby method call. The arguments can be passed to a generic function like toRubyValue that can be overloaded for various Nim and C types to automatically convert them to the right Ruby type.
2) Calling Nim from Ruby
In most scripting languages, there is a way to register a foreign type, often described in a particular data structure that has to be populated once per exported type. You can use a bit of generic programming and Nim's .global. vars to automatically create and cache the required data structure for each type that was passed to Ruby through the dot operators. There will be a generic proc like getRubyTypeDesc(T: typedesc) that may rely on typeinfo, typetraits or some overloaded procs supplied by user, defining what has to be exported for the type.
Now, if you really want to rely on mruby (because you have experience with it for example), you can look into using the .emit. pragma to directly output pieces of mruby code. You can then ask the Nim compiler to generate only source code, which you will compile in a second step or you can just change the compiler executable, which Nim will call when compiling the project (this is explained in the same section linked above).
Here's what I've discovered so far.
Fetching the return value from an mruby execution is not as easy as I thought. That said, after much trial and error, this is the simplest way I've found to get some mruby code to execute:
const mrb_cc_flags = "-v -I/mruby_1.2.0_path/include/ -L/mruby_1.2.0_path/build/host/lib/"
const mrb_linker_flags = "-v"
const mrb_obj = "/mruby_1.2.0_path/build/host/lib/libmruby.a"
{. passC: mrb_cc_flags, passL: mrb_linker_flags, link: mrb_obj .}
{.emit: """
#include <mruby.h>
#include <mruby/string.h>
""".}
proc ruby_raw(str:cstring):cstring =
{.emit: """
mrb_state *mrb = mrb_open();
if (!mrb) { printf("ERROR: couldn't init mruby\n"); exit(0); }
mrb_load_string(mrb, `str`);
`result` = mrb_str_to_cstr(mrb, mrb_funcall(mrb, mrb_top_self(mrb), "test_func", 0));
mrb_close(mrb);
""".}
proc ruby*(str:string):string =
echo ruby_raw("def test_func\n" & str & "\nend")
"done"
let resp = ruby """
puts 'this was a puts from within ruby'
"this is the response"
"""
echo(resp)
I'm pretty sure that you should be able to omit some of the compiler flags at the start of the file in a well configured environment, e.g. by setting LD_LIBRARY_PATH correctly (not least because that would make the code more portable)
Some of the issues I've encountered so far:
I'm forced to use mrb_funcall because, for some reason, clang seems to think that the mrb_load_string function returns an int, despite all the c code I can find and the documentation and several people online saying otherwise:
error: initializing 'mrb_value' (aka 'struct mrb_value') with an expression of incompatible type 'int'
mrb_value mrb_out = mrb_load_string(mrb, str);
^ ~~~~~~~~~~~~~~~~~~~~~~~~~
The mruby/string.h header is needed for mrb_str_to_cstr, otherwise you get a segfault. RSTRING_PTR seems to work fine also (which at least gives a sensible error without string.h), but if you write it as a one-liner as above, it will execute the function twice.
I'm going to keep going, write some slightly more idiomatic nim, but this has done what I needed for now.
I am wondering why the following failed to work.
(1=$:#([:+/[:*:#"."0":)`]#.(e.&1 4))7
1
and
(({&('no';'yes'))#(1=$:#([:+/[:*:#"."0":)`]#.(e.&1 4)))7
┌──┐
│no│
└──┘
I would expect it to return yes since it is taking the second argument (because the first expression evaluates to 1). Could anybody please explain?
Thanks.
I must admit that it is difficult to figure out what you are trying to do, but the issue i think is your use of Self-Reference ($:).
The description of Self-Reference in the J dictionary states '$: denotes the longest verb that contains it.' http://www.jsoftware.com/help/dictionary/d212.htm
By combining
({&('no';'yes')) with your original verb
(1=$:#([:+/[:*:#"."0":)`]#.(e.&1 4))
You have actually changed the verb that $: self references and I believe this results in the (unexpected) behaviour. I hope that this helps. If you can give a reason for using $: I might be able to give a better answer as to why your verb works this way. I tend to use it very little, as there are usually better solutions in J.
Just another thought. You could define the parts of the verb you are looking to create separately and this would limit the scope of the $: and give you the behaviour that you would like.
choose=: (1=$:#([:+/[:*:#"."0":)`]#.(e.&1 4))
display=:({&('no';'yes'))
display # choose 7
┌───┐
│yes│
└───┘
Is it possible to turn off abbreviation in getopt_long()? From the man page:
Long option names may be abbreviated if the abbreviation is unique or is an exact match for >some defined option.
I want to do this because the specification I have received for a piece of code requires full-length exact match of the flags, and there are many flags.
Codeape,
It appears there isn't a way to disable the abbreviation feature. You aren't alone in wishing for this feature. See: http://sourceware.org/bugzilla/show_bug.cgi?id=6863
Unfortunately, It seems the glibc developers don't want the option as the bug report linked above was resolved with "WONTFIX". You may be out of luck here :-\
If you use argp_parse() instead of getopt() (highly reccommended, BTW), you can access the exact flag entered by the user through
state->argv[ state->next - 2 ]
It's a bit of a hack, but should work.
This is not perfect solution but you can check exact arg given by a user after calling getopt_long() (normally within switch) like below:
if (strcmp(argv[optind-1], "--longoption") == 0)
optind points a next argument that you need to process. Thus, you can access the original arg using optind-1.
When messing around with Haskell using GHC, I can use various meta-commands like :i or :t to find out some information about an identifier. In REBOL, I can use functions like help and sometimes source to get extremely detailed information on a REBOL word.
If such a facility exists for J, I've somehow missed it. Do any J-ers out there know of anything built-in?
Highlight the primitive or J library verb and hit Ctrl-F1. Instant help in html form in your browse if it's a primitive, script documentation for J library verbs.
EDIT:
Or you can use the verb defined to do that, help_j_:
help_j_ 'i.' NB. Opens didot.htm
help_j_ 'help_j_' NB. Opens \system\extras\util\jadefull.ijs in scriptdoc