The main idea of the code is this I load an expression from a file which has only 1 line like 100 + a + (x ^ 2)
I want to load it in a function and check if it's ok (so it is not like )) + 5 2 a **). First I want to say that I know my checks are not covering all type of mistakes but we have to check only for some mistakes. First here is the code
main = do
contents <- readFile "file.txt"
let stringToCheck <- line contents
checkIfProper filter (/=' ') stringToCheck
As you can see I am really new to Haskell and I would like this to work and I would fix it step by step. I think logically it is fine and there are only syntax mistakes that I can't understand.
My first question is at the begining of the main I load from a file.txt this file has only 1 line and I take it in the stringToCheck and then I want to use filter on it to remove all spaces but this doesn't work. If I call the filter on a string I write down at the moment it's fine but when I load it from the file it has problems I guess I don't take the line properly so how to do this?
How do you take a string properly from a file and use it as a variable in other function?
main = do
contents <- readFile "file.txt"
So far everything fine. You've read in the file in IO, and used the do-block syntax with <- correctly. For everything underneath, contents is a String variable that holds the contents of the file.
let stringToCheck <- line contents
Here, you do not need this special assignment syntax: at this point as I said, contents is a "pure" value, so anything you use it for is purely functional and you can use ordinary =. That's always done in let blocks. So...
let stringToCheck = line contents
Well, that doesn't work because there's no line function. There is lines, which splits up a text in a list of strings, each representing a line; to retrieve the first one use
let stringToCheck = head $ lines contents
but if the file only has one line then this is equivalent to simply stringToCheck = contents.
checkIfProper filter (/=' ') stringToCheck
Now, here is suppose you mean checkIfProper (filter (/=' ') stringToCheck): the function checkIfProper takes just a single argument, but if you just write out a composite expression that is misparsed as a couple of different arguments, i.e. checkIfProper filter (/=' ') stringToCheck actually means what in un-curried languages would be written checkIfProper(filter, (/=' '), stringToCheck). I don't think you mean that!
The idiomatic way of writing it in Haskell is
checkIfProper $ filter (/=' ') stringToCheck
The resulting main might still not compile: the result of checkIfProper needs to have type IO () so you can simply append it to a do block as in main, but apparently it has type String -> Bool. Perhaps you want the result printed out, that's done with
print . checkIfProper $ filter (/=' ') stringToCheck
In case you're not familiar with . and $: you can read an expression like
f . g . h $ x + y
as
f (g (h (x + y)))
Related
I am trying to exclude certain words from dictionary file.
# cat en.txt
test
testing
access/p
batch
batch/n
batches
cross
# cat exclude.txt
test
batch
# grep -vf exclude.txt en.txt
access/p
cross
The words like "testing" and "batches" should be included in the results.
expected result:
testing
access/p
batches
cross
Because the word "batch" may or may not be followed by a slash "/". There can be one or more tags after slash (n in this case). But the word "batches" is a different word and should not match with "batch".
I would harness GNU AWK for this task following way, let en.txt content be
test
testing
access/p
batch
batch/n
batches
cross
and exclude.txt content be
test
batch
then
awk 'BEGIN{FS="/"}FNR==NR{arr[$1];next}!($1 in arr)' exclude.txt en.txt
gives output
testing
access/p
batches
cross
Explanation: I inform GNU AWK that / is field separator (FS), then when processing first file (where number of row globally is equal to number of row inside file, that is FNR==NR) I simply use 1st column value as key in array arr and then go to next line, so nothing other happens, for 2nd (and following files if present) I select lines whose 1st column is not (!) one of keys of array arr.
(tested in GNU Awk 5.0.1)
Using grep matching whole words:
grep -wvf exclude.txt en.txt
Explanation (from man grep)
-w --word-regexp Select only those lines containing matches that form whole words.
-v --invert-match Invert the sense of matching, to select non-matching lines.
-f -f FILE Obtain patterns from FILE, one per line.
Output
testing
access/p
batches
cross
Since there are many words in a dictionary that may have a root in one of those to exclude we cannot conveniently† use a look-up hash (built of the exclude list), but have to check all of them. One way to do that more efficiently is to use an alternation pattern built from the exclude list
use warnings;
use strict;
use feature 'say';
use Path::Tiny; # to read ("slurp") a file conveniently
my $excl_file = 'exclude.txt';
my $re_excl = join '|', split /\n/, path($excl_file)->slurp;
$re_excl = qr($re_excl);
while (<>) {
if ( m{^ $re_excl (?:/.)? $}x ) {
# say "Skip printing (so filter out): $_";
next;
}
say;
}
This is used as program.pl dictionary-filename and it prints the filtered list.
Here I've assumed that what may follow the root-word to exclude is / followed by one character, (?:/.)?, since examples in the question use that and there is no precise statement on it. The pattern also assumes no spaces around the word.
Please adjust as/if needed for what may actually follow /. For example, it'd be (?:/.+)? for at least one character, (?:/[np])? for any character from a specific list (n or p), (?:[^xy]+)? for any characters not in the given list, etc.
The qr operator forms a proper regex pattern.
† Can still first strip non-word endings, then use a look-up, then put back those endings
use Path::Tiny; # to read a file conveniently
my %lu = map { $_ => 1 } path($excl_file)->lines({ chomp => 1 });
while (<>) {
chomp;
# [^\w-] protects hyphenated words (or just use \W)
# Or: s{(/.+$}{}g; if "/" is the only possibility
s/([^\w-].+)$//g;
next if exists $lu{$_};
$_ .= $1 if $1;
say;
}
This will be far more efficient, on large dictionaries and long lists of exclude words.
However, it is far more complex and probably fails some (unstated) requirements
In reference to this question,
How to download and get values from JSON file using VBScript or batch file?
how to get the values from JSON file that looks like this,
["AA-BB-CC-MAKE-SAME.json","SS-ED-SIXSIX-TENSE.json","FF-EE-EE-EE-WW.json","ZS-WE-AS-FOUR-MINE.json","DD-RF-LATERS-LATER.json","FG-ER-DC-ED-FG.json"]
using AppleScript in MAC OS?
Here is part of VBScript code in Windows provided by Hackoo,
strJson = http.responseText
Result = Extract(strJson,"(\x22(.*)\x22)")
Arr = Split(Result,",")
For each Item in Arr
wscript.echo Item
Next
'******************************************
Function Extract(Data,Pattern)
Dim oRE,oMatches,Match,Line
set oRE = New RegExp
oRE.IgnoreCase = True
oRE.Global = True
oRE.Pattern = Pattern
set oMatches = oRE.Execute(Data)
If not isEmpty(oMatches) then
For Each Match in oMatches
Line = Line & Trim(Match.Value) & vbCrlf
Next
Extract = Line
End if
End Function
'******************************************
In MAC OS AppleScript I only need the code to get the values of the JSON file to a single array of string values. The above shown example above the VBScript is the how JSON file contents looks like.
Short answer: Unfortunately, AppleScript doesn't provide a built-in feature to parse JSON which is analogous to JavaScript's JSON.parse() method.
Below are a couple of solutions:
Solution 1: Requires a third party plug-in to be installed, which may not always be feasible.
Solution 2: Does not require any third party plug-in to be installed, and instead utilizes tools/features built-in to macOS as standard.
Solution 1:
If you have the luxury of being able to install a third-party plugin on your users systems then you can install JSON Helper for AppleScript (As suggested by #user3439894 in the comments).
Then use it in your AppleScript as follows:
set srcJson to read POSIX file (POSIX path of (path to home folder) & "Desktop/foobar.json")
tell application "JSON Helper" to set myList to read JSON from srcJson
Explanation:
On line 1 we read the contents of the .json file and assign it to the variable named srcJson.
Note You'll need to change the path part (i.e. Desktop/foobar.json) as necessary.
On line 2 we parse the contents using the JSON Helper plug-in. This assigns each item of the source JSON Array to a new AppleScript list. The resultant AppleScript list is assigned to a variable named myList.
Solution 2:
By utilizing tools built-in to macOS as standard, you can also do the following via AppleScript. This assumes that your JSON file is valid and contains a single Array only:
set TID to AppleScript's text item delimiters
set AppleScript's text item delimiters to ","
set myList to text items of (do shell script "tr ''\\\\n\\\\r'' ' ' <~/Desktop/foobar.json | sed 's/^ *\\[ *\"//; s/ *\" *\\] *$//; s/\" *, *\"/,/g;'")
set AppleScript's text item delimiters to TID
Note: you'll need to change the path part (i.e. ~/Desktop/foobar.json) as necessary.
Also, if your .json filename includes a space(s) you'll need to escape them with \\. For instance ~/Desktop/foo\\ bar.json
Explanation:
On line 1 AppleScript's current text item delimiters are assigned to a variable named TID.
On line 2 AppleScript's text item delimiters are set to a comma - this will help when extracting each individual value from the source JSON Array and assigning each value to a new AppleScript list.
On line 3 a shell script is executed via the do shell script command, which performs the following:
Reads the content of the source .json file via the part which reads ~/Desktop/foobar.json. This path currently assumes the file is named foobar.json and resides in your Desktop folder (You'll need to change this path to wherever your actual file exists).
The content of foobar.json is redirected, (note the < before the filepath), to tr (i.e. the part which reads: tr ''\\\\n\\\\r'' ' '). This translation will replace any newline characters which may exists in the contents of the source .json Array with space characters. This ensures the contents of foobar.json is transformed to one line.
Note: A JSON Array can contain newlines between each item and still be valid, so although the example JSON given in your question appears on one line - it is not a requirement of this solution as it will handle multi-line too.
The one line of text is then piped to sed's s command for further processing (i.e. the part which reads: | sed 's/^ *\\[ *\"//; s/ *\" *\\] *$//; s/\" *, *\"/,/g;').
The syntax of the s command is 's/regexp/replacement/flags'.
Let's breakdown each s command to further understand what is happening:
s/^ *\\[ *\"// removes the opening square bracket [, which may be preceded or followed by zero or more space characters, and the following double quote (i.e. the first occurrence) from the beginning of the string.
s/ *\" *\\] *$// removes the closing square bracket ], which may be preceded or followed by zero or more space characters, and the preceding double quote (i.e. the last occurrence) from the end of the string.
s/\" *, *\"/,/g replaces single commas, (which may be preceded with zero or more spaces, and/or followed by zero or more spaces) with a single comma.
The initial part on line 3 which reads; set myList to text items of ... utilizes text items to read the String into an AppleScript list using commas as delimiters to determine each item of the list. The resultant Array is assigned to a variable named myList.
On line 4 AppleScript's text item delimiters are restored to their original value.
Utilizing a variable for the source JSON filepath.
If you want to utilize a variable for the filepath to the source .json file then you can do something like this instead:
set srcFilePath to quoted form of (POSIX path of (path to home folder) & "Desktop/foobar.json")
set TID to AppleScript's text item delimiters
set AppleScript's text item delimiters to ","
set myList to text items of (do shell script "tr ''\\\\n\\\\r'' ' ' <" & srcFilePath & " | sed 's/^ *\\[ *\"//; s/ *\" *\\] *$//; s/\" *, *\"/,/g;'")
set AppleScript's text item delimiters to TID
Note This is very much the same as the first example. The notable differences are:
On the first line we assign the filepath to a variable named srcFilePath.
In the do shell script we reference the srcFilePath variable.
Additional note regarding JSON escaped special characters: Solution 2 preserves any JSON escaped special characters which may be present in the values of source JSON array. However, Solution 1 will interpret them.
Caveats Solution 2 produces unexpected results when an item in the source JSON array includes a comma because a comma is used as a text item delimiters.
How to get the values from JSON file that looks like this,
["AA-BB-CC-MAKE-SAME.json","SS-ED-SIXSIX-TENSE.json","FF-EE-EE-EE-WW.json","ZS-WE-AS-FOUR-MINE.json","DD-RF-LATERS-LATER.json","FG-ER-DC-ED-FG.json"]
If you actually mean what you wrote, and that the contents of the JSON file is that list of six strings in a single array, formatted on a single line, the simplest way is to treat it as text, trim the opening and closing square brackets, then delimit its fields at every occurrence of a ,. Finally, each individual text item can have the surrounding quotes trimmed as well.
Examining the VBScript, it looks like it uses a very similar process, albeit with regular expressions, which AppleScript doesn't feature but which aren't especially necessary in this simple situation.
Let's assume that the JSON array above is stored in a file on your desktop called "myfile.json". Then:
set home to the path to home folder
set f to the POSIX path of home & "Desktop/myfile.json"
set JSONstr to read POSIX file f
# Trim square brackets
set JSONstr to text 2 thru -2 of JSONstr
# Delimit text fields using comma
set the text item delimiters to ","
set Arr to the text items of JSONstr
# Trim quotes of each item in Arr
repeat with a in Arr
set contents of a to text 2 thru -2 of a
end repeat
# The final array
Arr
I only need the code to get the values of the JSON file to a single array of string values. The above shown example above the VBScript is the how JSON file contents looks like.
The variable Arr now contains the array (referred to as lists in AppleScript) of string values. You can access a particular item in it like this:
item 2 of Arr --> "SS-ED-SIXSIX-TENSE.json"
A More General Solution
I've decided to include a more advanced way to handle JSON in an AppleScript, partly because I've been doing a lot of JSON processing quite recently and this is all fresh on my event horizon; but also to demonstrate that, using AppleScriptObjC, parsing even very complex JSON data is not only possible, but quite simple.
I don't think you'll need it in this specific case, but it could come in useful for some future situation.
The script has three sections: it starts off importing the relevant Objective-C framework that gives AppleScript additional powers; then, I define the actual handler itself, called JSONtoRecord, which I describe below. Lastly, comes the bottom of the script where you can enter your code and do whatever you like with it:
use framework "Foundation"
use scripting additions
--------------------------------------------------------------------------------
property ca : a reference to current application
property NSData : a reference to ca's NSData
property NSDictionary : a reference to ca's NSDictionary
property NSJSONSerialization : a reference to ca's NSJSONSerialization
property NSString : a reference to ca's NSString
property NSUTF8StringEncoding : a reference to 4
--------------------------------------------------------------------------------
on JSONtoRecord from fp
local fp
set JSONdata to NSData's dataWithContentsOfFile:fp
set [x, E] to (NSJSONSerialization's ¬
JSONObjectWithData:JSONdata ¬
options:0 ¬
|error|:(reference))
if E ≠ missing value then error E
tell x to if its isKindOfClass:NSDictionary then ¬
return it as record
x as list
end JSONtoRecord
--------------------------------------------------------------------------------
###YOUR CODE BELOW HERE
#
#
set home to the path to home folder
set f to the POSIX path of home & "Desktop/myfile.json"
JSONtoRecord from f
--> {"AA-BB-CC-MAKE-SAME.json", "SS-ED-SIXSIX-TENSE.json", ¬
--> "FF-EE-EE-EE-WW.json", "ZS-WE-AS-FOUR-MINE.json", ¬
--> "DD-RF-LATERS-LATER.json", "FG-ER-DC-ED-FG.json"}
At the bottom of the script, I've called the JSONtoRecord handler, passing it the location of myfile.json. One of the benefits of this handler is that it doesn't matter whether the file is formatted all on one line, or over many lines. It can also handle complex, nested JSON arrays.
In those instances, what it returns is a native AppleScript record object, with all the JSON variables stored as property values in the record. Accessing the variables then becomes very simple.
This is actually exactly what the JSON Helper application that a couple of people have already mentioned does under the hood.
The one criterion (other than the JSON file containing valid JSON data) is that the path to the file is a posix path written in full, e.g. /Users/CK/Desktop/myfile.json, and not ~/Desktop/myfile.json or, even worse, Macintosh HD:Users:CK:Desktop:myfile.json.
If you iterate over .VARIABLES and print each, any true variable can be printed correctly with the following rule:
print_variables: $(foreach V,$(.VARIABLES),print-$(V)) .phony_explicit
print-%: .phony_explicit; #echo "$* = \"$($*)\""
.PHONY: .phony_explicit ...
A 0- or 1-line function will still work, but any more will result in Syntax error: Unterminated quote string. Just one multiline function will break the entire print_variables rule. As a workaround, I have added ;\ to each line in my function definitions, but that won't fix existing multiline functions (either via includes from this makefile or via other makefiles including this one.) What can I do? Is there a container of just function variables, or a way to test if a variable is a function definition?
A simple minimal example would be easier to understand; this has nothing to do with .VARIABLES, pattern rules, etc. (and I'm not sure what the point of the .phony_explicit prereq is..)
define F
foo
bar
endef
print: ; echo "F = $(F)"
will show the problem:
echo "F = foo
/bin/sh: 1: Syntax error: Unterminated quoted string
This is because when make sees a variable that contains newlines in a recipe, it assumes that the newlines mean you want the lines of the variable to become lines in the recipe.
First in general you should use single-quotes around strings you send to the shell, unless you need the shell to expand them; it won't help in this situation but in general it's much safer.
There's no way to undo that, really. You have a number of options.
The first is to not use echo but instead use the make function info:
print-F: ; $(info F = "$(F)")
yields:
F = "foo
bar"
Another option is to use subst to replace the newlines with some other value. The new value cannot itself contain explicit newlines, but you can ask the shell to print a newline for you:
# Create a variable containing a single newline
# Note this must contain TWO newlines!
define NL
endef
print-F: printf 'F = "$(subst %,%%,$(subst $(NL),\n,$(F))"\n'
Yields:
printf 'F = "foo\nbar"\n'
F = "foo
bar"
One final option is to convert your makefile to use the .ONESHELL feature, but I assume that's a step too far just to get this debugging output available :).
I am trying to use a formatted string to identify the file location when using 'print -dpdf file_name' to write a plot (or figure) to a file.
I've tried:
k=1;
file_name = sprintf("\'/home/user/directory to use/file%3.3i.pdf\'",k);
print -dpdf file_name;
but that only gets me a figure written to ~/file_name.pdf which is not what I want. I've tried several other approaches but I cannot find an approach that causes the the third term (file_name, in this example) to be evaluated. I have not found any other printing function that will allow me to perform a formatted write (the '-dpdf' option) of a plot (or figure) to a file.
I need the single quotes because the path name to the location where I want to write the file contains spaces. (I'm working on a Linux box running Fedora 24 updated daily.)
If I compute the file name using the line above, then cut and paste it into the print statement, everything works exactly as I wish it to. I've tried using
k=1;
file_name = sprintf("\'/home/user/directory to use/file%3.3i.pdf\'",k);
print ("-dpdf", '/home/user/directory to use/file001.pdf');
But simply switching to a different form of print statement doesn't solve the problem,although now I get an error message:
GPL Ghostscript 9.16: **** Could not open the file '/home/user/directory to use/file001.pdf' .
**** Unable to open the initial device, quitting.
warning: broken pipe
if you use foo a b this is the same as foo ("a", "b"). In your case you called print ("-dpdf", "file_name")
k = 1;
file_name = sprintf ("/home/user/directory to use/file%3.3i.pdf", k);
print ("-dpdf", file_name);
Observe:
>> k=1;
>> file_name = sprintf ('/home/tasos/Desktop/a folder with spaces in it/this is file number %3.3i.pdf', k)
file_name = /home/tasos/Desktop/a folder with spaces in it/this is file number 001.pdf
>> plot (1 : 10);
>> print (gcf, file_name, '-dpdf')
Tadaaa!
So yeah, no single quotes needed. The reason single quotes work when you're "typing it by hand" is because you're literally creating the string on the spot with the single quotes.
Having said that, it's generally a good idea when generating absolute paths to use the fullfile command instead. Have a look at it.
Tasos Papastylianou #TasosPapastylianou provided great help. My problem is now solved.
I'm trying to figure out how, if even possible, can you perform more than one command within a Haskell function? For example, if I had:
foo [[a]] = print (head a) --AND -- map (head of everything but the first value)
How would I go about doing something like that? Is there a function which I could use in place of --AND-- which would allow me to perform both commands on the list of lists?
You're probably looking for do notation, which combined with properly formed pattern matching would get your desired behavior:
foo :: Show a => [[a]] -> IO ()
foo xs = do
print $ head $ head xs -- first value in the 2D list
print $ map head $ tail xs -- Skip first sublist with tail
Control.Arrow module has many combinators for wiring inputs to functions in interesting ways. Fanouts, fan-ins, etc.
On my phone, but something like print (<<<) head (&&&) map ( f . tail) $ input . That is wrong functions and order of operations, but gives a hint of the flavor. Check the module docs.