I have the next .ecl file:
:-lib(ic).
test(Valparaiso, Olmue):-
Valparaiso :: 1..10,
Olmue :: 1..10,
2*Valparaiso + 1*Olmue #<= 10,
1*Valparaiso + 2*Olmue #<= 8,
labeling(Valparaiso),
labeling(Olmue).
So I get the next error:
calling an undefined procedure 2 * A + 1 * B #<= 10 in module eclipse
I use ECLiPSe 7.0 for run that script.
That's something Prolog/ECLiPSe beginners occasionally stumble over: The "less-equal" sign is =<, not <= as in many other languages. Best remembered by visualizing the shape of the operator:
It's actually more beautiful, isn't it? As to why it was done this way, folklore says that one wanted to reserve the <= as a left arrow or reverse implication symbol.
Related
I inherited this code from a former co-worker, and it's giving me Invalid redo (SyntaxError) on the redo. Was there an older version of Ruby where this would've worked? I've tried 3, 2.7, 2.5, and 2.3, all without success.
def check_rate_limit(client, x, spinner)
if client.rate_limit.remaining <= x
spinner.error('ERROR: Rate limit exceeded!')
spinner = TTY::Spinner.new("[:spinner] Rate limit resets in #{client.rate_limit.resets_in + 10} seconds ...", format: :classic)
spinner.auto_spin
sleep(client.rate_limit.resets_in + 10) # additional 10 second cooldown
spinner.success
spinner = TTY::Spinner.new("[:spinner] Continuing ...", format: :classic)
redo
end
end
(Replacing if with while seems to do the trick, but my co-workers code ran before and I want to know why...)
I keep getting this negative argument error when running this code in the Codewars IDE. It runs fine in terminal but in Codewars it both passes the test and runs this error message simultaneously.
STDERR
main.rb:5:in `*': negative argument (ArgumentError)
from main.rb:5:in `maskify'
from main.rb:9:in `<main>'
The code is
def maskify(cc)
x = cc.to_s
y = "#" * (x.length - 4)
return y + x.slice(-4..-1)
end
I'm new to Ruby but I've not heard anywhere that it has a problem with negative numbers being used in .slice. Am I missing something here? Thanks.
You're not considering cases when cc is shorter than 4 symbols.
And expression "#" * (x.length - 4) raises the error because you can't multiply a string by a negative number.
Try to use Array#max method to handle this:
"#" * [x.length - 4, 0].max
What is the best way to increase the last part of a version by 1 (without the use of libraries).
Examples:
Gem::Version.new("2.0.31") to Gem::Version.new("2.0.32")
Gem::Version.new("2.0.3.0") to Gem::Version.new("2.0.3.1")
If the output is a string, that's ok too
Use Gem::Version#segments:
Gem::Version.new("2.0.31").
segments.
dup.
tap { |segments| segments.push(segments.pop.succ) }.
join('.')
#⇒ "2.0.32"
Here's a helper method I've used as part of rake tasks before, for version bumping.
Feel free to extend it as per your needs - e.g. if you want to add a forth number; or support versions named alpha-x or pre-x; or support an option for 'bump the last digit' (regardless of how many digits there are).
However, I'd be inclined not to support a 'bump the last digit' option, as this is quite ambiguous.
def bump(version, type)
major, minor, patch = version.split('.').map(&:to_i)
bumped = case type
when :major
[major + 1, 0, 0]
when :minor
[major, minor + 1, 0]
when :patch
[major, minor, patch + 1]
else
raise "Don't know how to bump for #{type}"
end
bumped.join('.')
end
bump("2.1.31", :patch) #=> "2.1.32"
bump("2.1.31", :minor) #=> "2.2.0"
bump("2.1.31", :major) #=> "3.0.0"
I have a postscript file when i try to convert it into pdf or open it with postscript it gives the following error
undefined in execform
I am trying to fix this error. But there is no solution i found. Kindly Help me understand the issue.
This is postscript file
OK so a few observations to start;
The file is 8 pages long, uses many forms, and the first form it uses has nested forms. This really isn't suitable as an example file, you are expecting other programmers to dig through a lot of extraneous cruft to help you out. When you post an example, please try and reduce it to just the minimum required to reproduce the problem.
Have you actually tried to debug this problem yourself ? If so what did you do ? (and why didn't you start by reducing the file complexity ?)
I don't want to be offensive, but this is the third rather naive posting you've made recently, do you have much experience of PostScript programming ? Has anyone offered you any training in the language ? It appears you are working on behalf of a commercial organisation, you should talk to your line manager and try and arrange some training if you haven't already been given some.
The PostScript program does not give the error you stated
undefined in execform
In fact the error is a Ghostscript-specific error message:
Error: /undefined in --.execform1--
So that's the .execform1 operator (note the leading '.' to indicate a Ghostscript internal operator). That's only important because firstly its important to accurately quote error messages, and secondly because, for someone familiar with Ghostscript, it tells you that the error occurs while executing the form PaintProc, not while executing the execform operator.
After considerably reducing of the complexity of the file, the problem is absolutely nothing to do with the use of Forms. The offending Form executes code like this:
2 RM
0.459396 w
[(\0\1\0\2)]435.529999 -791.02002 T
(That's the first occurrence, and its where the error occurs)
That executes the procedure named T which is defined as:
/T{neg _LY add /_y ed _LX add /_x ed/_BLSY _y _BLY sub D/_BLX _x D/_BLY _y D _x _y TT}bd
Obviously that's using a number of other functions defined in the prolog, but the important point is that it executes TT which is defined as :
/TT{/_y ed/_x ed/_SX _x _LX sub D/_SY _y _LY sub D/_LX _x D/_LY _y D _x _y m 0 _rm eq{ dup type/stringtype eq{show}{{ dup type /stringtype eq{show}{ 0 rmoveto}?}forall}?} if
1 _rm eq {gsave 0 _scs eq { _sr setgray}if 1 _scs eq { _sr _sg _sb setrgbcolor}if 2 _scs eq { _sr _sg _sb _sk setcmykcolor} if dup type/stringtype eq{true charpath }{{dup type /stringtype eq{true charpath } { 0 rmoveto}?}forall}? S grestore} if
2 _rm eq {gsave 0 _fcs eq { _fr setgray}if 1 _fcs eq { _fr _fg _fb setrgbcolor}if 2 _fcs eq { _fr _fg _fb _fk setcmykcolor} if dup type/stringtype eq{true charpath }{{dup type /stringtype eq{true charpath } { 0 rmoveto}?}
forall}? gsave fill grestore 0 _scs eq { _sr setgray}if 1 _scs eq { _sr _sg _sb setrgbcolor}if 2 _scs eq { _sr _sg _sb _sk setcmykcolor}if S grestore} if
Under the conditions holding at the time TT is executed (RM sets _rm to 2), we go through this piece of code:
gsave 0 _fcs eq
However, _fcs is initially undefined, and only defined when the /fcs function is executed. Your program never executes /fcs so _fcs is undefined, leading to the error.
Is there a reason why you are defining each page in a PostScript Form ? This is not optimal, if the interpreter actually supports Forms then you are using up VM for no useful purpose (since you only execute each Form once).
If its because the original PDF input uses PDF Form XObjects I would recommend that you don't try and reproduce those in PostScript. Reuse of Form XObjects in PDF is rather rare (it does happen but non-reuse is much more common). The loss of efficiency due to describing PostScript Forms for each PDF Form XObject for all the files where the form isn't reused exceeds the benefit for the rare cases where it would actually be valuable.
I am new to Haskell. Previously I have programmed in Python and Java. When I am debugging some code I have a habit of littering it with print statements in the middle of code. However doing so in Haskell will change semantics, and I will have to change my function signatures to those with IO stuff. How do Haskellers deal with this? I might be missing something obvious. Please enlighten.
Other answers link the official doco and the Haskell wiki but if you've made it to this answer let's assume you bounced off those for whatever reason. The wikibook also has an example using Fibonacci which I found more accessible. This is a deliberately basic example which might hopefully help.
Let's say we start with this very simple function, which for important business reasons, adds "bob" to a string, then reverses it.
bobreverse x = reverse ("bob" ++ x)
Output in GHCI:
> bobreverse "jill"
"llijbob"
We don't see how this could possibly be going wrong, but something near it is, so we add debug.
import Debug.Trace
bobreverse x = trace ("DEBUG: bobreverse" ++ show x) (reverse ("bob" ++ x))
Output:
> bobreverse "jill"
"DEBUG: bobreverse "jill"
llijbob"
We are using show just to ensure x is converted to a string correctly before output. We also added some parenthesis to make sure the arguments were grouped correctly.
In summary, the trace function is a decorator which prints the first argument and returns the second. It looks like a pure function, so you don't need to bring IO or other signatures into the functions to use it. It does this by cheating, which is explained further in the linked documentation above, if you are curious.
Read this. You can use Debug.Trace.trace in place of print statements.
I was able to create a dual personality IO / ST monad typeclass, which will print debug statements when a monadic computation is typed as IO, them when it's typed as ST. Demonstration and code here: Haskell -- dual personality IO / ST monad? .
Of course Debug.Trace is more of a swiss army knife, especially when wrapped with a useful special case,
trace2 :: Show a => [Char] -> a -> a
trace2 name x = trace (name ++ ": " ++ show x) x
which can be used like (trace2 "first arg" 3) + 4
edit
You can make this even fancier if you want source locations
{-# LANGUAGE TemplateHaskell #-}
import Language.Haskell.TH
import Language.Haskell.TH.Syntax as TH
import Debug.Trace
withLocation :: Q Exp -> Q Exp
withLocation f = do
let error = locationString =<< location
appE f error
where
locationString :: Loc -> Q Exp
locationString loc = do
litE $ stringL $ formatLoc loc
formatLoc :: Loc -> String
formatLoc loc = let file = loc_filename loc
(line, col) = loc_start loc
in concat [file, ":", show line, ":", show col]
trace3' (loc :: String) msg x =
trace2 ('[' : loc ++ "] " ++ msg) x
trace3 = withLocation [| trace3' |]
then, in a separate file [from the definition above], you can write
{-# LANGUAGE TemplateHaskell #-}
tr3 x = $trace3 "hello" x
and test it out
> tr3 4
[MyFile.hs:2:9] hello: 4
You can use Debug.Trace for that.
I really liked Dons short blog about it:
https://donsbot.wordpress.com/2007/11/14/no-more-exceptions-debugging-haskell-code-with-ghci/
In short: use ghci, example with a program with code called HsColour.hs
$ ghci HsColour.hs
*Main> :set -fbreak-on-exception
*Main> :set args "source.hs"
Now run your program with tracing on, and GHCi will stop your program at the call to error:
*Main> :trace main
Stopped at (exception thrown)
Ok, good. We had an exception… Let’s just back up a bit and see where we are. Watch now as we travel backwards in time through our program, using the (bizarre, I know) “:back” command:
[(exception thrown)] *Main> :back
Logged breakpoint at Language/Haskell/HsColour/Classify.hs:(19,0)-(31,46)
_result :: [String]
This tells us that immediately before hitting error, we were in the file Language/Haskell/HsColour/Classify.hs, at line 19. We’re in pretty good shape now. Let’s see where exactly:
[-1: Language/Haskell/HsColour/Classify.hs:(19,0)-(31,46)] *Main> :list
18 chunk :: String -> [String]
vv
19 chunk [] = head []
20 chunk ('\r':s) = chunk s -- get rid of DOS newline stuff
21 chunk ('\n':s) = "\n": chunk s
^^