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Return the first line of a String in Haskell
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Just a simple question, my code is complete. It takes an input file, breaks it into lines, reads the file line by line, does the conversions, which is in this case, turns certain things into HTML format (ex: #This is a line into a line with H1 HTML tags, formatting it into a header). The only thing I have left is to take the First line of code, and print that code into the browser tab. Also, the body, or tail must be printed into the window, not the tab. So the first line of my .txt file is The Title! which I want to show in the tab of the web browser. Here is something I have for that:
formatToHTML :: String -> String
formatToHTML [] = []
formatToHTML x
| head x == --any char = "<title>" ++ head ++ "</title>"
| tail x == --rest of file = "<body>" ++ tail ++ "</tail>"
| otherwise = null
or
formatToHTML :: [String] -> String
formatToHTML = unlines. map (show) "<title>" ++ head ++ </title>" $ lines
I dont want to, or I think even need to use guards here, but I cant think of a shorter way to do my task.
I would call this from my main method before I output my file to html.
Also, I know its a amateur haskell question. but how would I represent any char. Say, I want to say, if the head of x exists, print the head with the title tags. print tail with body tags. Help? Thank You
My guess of what you want is:
formatHtml :: [String] -> String
formatHtml [] = ""
formatHtml (x:xs) = unlines theLines
where theLines = [ "<title>" ++ ...convert x to html... ++ "</title>",
"<body>" ] ++ map toHtml xs ++ [ "</body>" ]
toHtml :: String -> String
toHmtl str = ...converts str to HTML...
Example:
formatHtml [ "the title", "body line 1", "body line2" ]
results in:
<title>the title</title>
<body>
body line 1
body line 2
</body>
You still have to define the toHtml function and decide how to convert the first line to the inner html of the tag.
Related
Here is my code that does CSV parsing, using the text and attoparsec
libraries:
import qualified Data.Attoparsec.Text as A
import qualified Data.Text as T
-- | Parse a field of a record.
field :: A.Parser T.Text -- ^ parser
field = fmap T.concat quoted <|> normal A.<?> "field"
where
normal = A.takeWhile (A.notInClass "\n\r,\"") A.<?> "normal field"
quoted = A.char '"' *> many between <* A.char '"' A.<?> "quoted field"
between = A.takeWhile1 (/= '"') <|> (A.string "\"\"" *> pure "\"")
-- | Parse a block of text into a CSV table.
comma :: T.Text -- ^ CSV text
-> Either String [[T.Text]] -- ^ error | table
comma text
| T.null text = Right []
| otherwise = A.parseOnly table text
where
table = A.sepBy1 record A.endOfLine A.<?> "table"
record = A.sepBy1 field (A.char ',') A.<?> "record"
This works well for a variety of inputs but is not working in case that there
is a trailing \n at the end of the input.
Current behaviour:
> comma "hello\nworld"
Right [["hello"],["world"]]
> comma "hello\nworld\n"
Right [["hello"],["world"],[""]]
Wanted behaviour:
> comma "hello\nworld"
Right [["hello"],["world"]]
> comma "hello\nworld\n"
Right [["hello"],["world"]]
I have been trying to fix this issue but I ran out of idaes. I am almost
certain that it will have to be something with A.endOfInput as that is the
significant anchor and the only "bonus" information we have. Any ideas on how
to work that into the code?
One possible idea is to look at the end of the string before running the
Attoparsec parser and removing the last character (or two in case of \r\n)
but that seems to be a hacky solution that I would like avoid in my code.
Full code of the library can be found here: https://github.com/lovasko/comma
I wanted to extract an email message content. It is in html content, used the BeautifulSoup to fetch the From, To and subject. On fetching the body content, it fetches the first line alone. It leaves the remaining lines and paragraph.
I miss something over here, how to read all the lines/paragraphs.
CODE:
email_message = mail.getEmail(unreadId)
print (email_message['From'])
print (email_message['Subject'])
if email_message.is_multipart():
for payload in email_message.get_payload():
bodytext = email_message.get_payload()[0].get_payload()
if type(bodytext) is list:
bodytext = ','.join(str(v) for v in bodytext)
else:
bodytext = email_message.get_payload()[0].get_payload()
if type(bodytext) is list:
bodytext = ','.join(str(v) for v in bodytext)
print (bodytext)
parsedContent = BeautifulSoup(bodytext)
body = parsedContent.findAll('p').getText()
print body
Console:
body = parsedContent.findAll('p').getText()
AttributeError: 'list' object has no attribute 'getText'
When I use
body = parsedContent.find('p').getText()
It fetches the first line of the content and it is not printing the remaining lines.
Added
After getting all the lines from the html tag, I get = symbol at the end of each line and also   ; , < is displayed.How to overcome those.
Extracted text:
Dear first,All of us at GenWatt are glad to have xyz as a
customer. I would like to introduce myself as your Account
Manager. Should you = have any questions, please feel free to
call me at or email me at ash= wis#xyz.com. You
can also contact GenWatt on the following numbers: Main:
810-543-1100Sales: 810-545-1222Customer Service & Support:
810-542-1233Fax: 810-545-1001I am confident GenWatt will serve you
well and hope to see our relationship=
Let's inspect the result of soup.findAll('p')
python -i test.py
----------
import requests
from bs4 import BeautifulSoup
bodytext = requests.get("https://en.wikipedia.org/wiki/Earth").text
parsedContent = BeautifulSoup(bodytext, 'html.parser')
paragraphs = soup.findAll('p')
----------
>> type(paragraphs)
<class 'bs4.element.ResultSet'>
>> issubclass(type(paragraphs), list)
True # It's a list
Can you see? It's a list of all paragraphs. If you want to access their content you will need iterate over the list or access an element by an index, like a normal list.
>> # You can print all content with a for-loop
>> for p in paragraphs:
>> print p.getText()
Earth (otherwise known as the world (...)
According to radiometric dating and other sources of evidence (...)
...
>> # Or you can join all content
>> content = []
>> for p in paragraphs:
>> content.append(p.getText())
>>
>> all_content = "\n".join(content)
>>
>> print(all_content)
Earth (otherwise known as the world (...) According to radiometric dating and other sources of evidence (...)
Using List Comprehension your code will looks like:
parsedContent = BeautifulSoup(bodytext)
body = '\n'.join([p.getText() for p in parsedContent.findAll('p')]
When I use
body = parsedContent.find('p').getText()
It fetches the first line of the content and it is not printing the
remaining lines.
Do parsedContent.find('p') is exactly the same that do parsedContent.findAll('p')[0]
>> parsedContent.findAll('p')[0].getText() == parsedContent.find('p').getText()
True
I had a question concerning some basic transformations in Haskell.
Basically, I have a written Input file, named Input.md. This contains some markdown text that is read in my project file, and I want to write a few functions to do transformations on the text. After completing these functions under a function called convertToHTML, I have output the file as an .html file in the correct format.
module Main
(
convertToHTML,
main
) where
import System.Environment (getArgs)
import System.IO
import Data.Char (toLower, toUpper)
process :: String -> String
process s = head $ lines s
convertToHTML :: String -> String
convertToHTML str = do
x <- str
if (x == '#')
then "<h1>"
else return x
--convertToHTML x = map toUpper x
main = do
args <- getArgs -- command line args
let (infile,outfile) = (\(x:y:ys)->(x,y)) args
putStrLn $ "Input file: " ++ infile
putStrLn $ "Output file: " ++ outfile
contents <- readFile infile
writeFile outfile $ convertToHTML contents
So,
How would I read through my input file, and transform any line that starts with a # to an html tag
How would I read through my input file once more and transform any WORD that is surrounded by _word_ (1 underscore) to another html tag
Replace any Character with an html string.
I tried using such functions such as Map, Filter, ZipWith, but could not figure out how to iterate through the text and transform each text. Please if anybody has any suggestions. I've been working on this for 2 days straight and have a bunch of failed code to show for a couple of weeks and have a bunch of failed code to show it.
I tried using such functions such as Map, Filter, ZipWith, but could not figure out how to iterate through the text and transform each text.
Because they work on appropriate element collection. And they don't really "iterate"; you simply have to feed the appropriate data. Let's tackle the # problem as an example.
Our file is one giant String, and what we'd like is to have it nicely split in lines, so [String]. What could do it for us? I have no idea, so let's just search Hoogle for String -> [String].
Ah, there we go, lines function! Its counterpart, unlines, is also going to be useful. Now we can write our line wrapper:
convertHeader :: String -> String
convertHeader [] = [] -- that prevents us from calling head on an empty line
convertHeader x = if head x == '#' then "<h1>" ++ x ++ "</h1>"
else x
and so:
convertHeaders :: String -> String
convertHeaders = unlines . map convertHeader . lines
-- ^String ^[String] ^[String] ^String
As you can see the function first converts the file to lines, maps convertHeader on each line, and the puts the file back together.
See it live on Ideone
Try now doing the same with words to replace your formatting patterns. As a bonus exercise, change convertHeader to count the number of # in front of the line and output <h1>, <h2>, <h3> and so on accordingly.
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I would like to output a table in html format.
Basically I would like something like :
[[a]] -> <table>
What is the easiest way to do so ?
The easiest way to generate Html is probably blaze:
import Text.Blaze.Html5 (table, td, tr, toHtml, ToMarkup, Html)
import Control.Monad (forM_, mapM_)
myTable :: (ToMarkup a) => [[a]] -> Html
myTable xs = table $ forM_ xs (tr . mapM_ (td . toHtml))
Note that you need to use renderHtml from Text.Blaze.Renderer.* to get a ByteString, String or Text.
Edit: During writing the answer #Zeta already posted a better solution using blaze-html. So I recommend using his solution (see section "Words of Warning" for the listening of this solutions disadvantages...) ;-)
Here is an implementation:
-- file test.hs:
insideTag :: String -> String -> String
insideTag tag content = "<" ++ tag ++ ">" ++ content ++ "</" ++ tag ++ ">"
toTable :: Show a => [[a]] -> String
toTable = insideTag "table" . concatMap (insideTag "tr") . map (concatMap (insideTag "td" . show))
main :: IO ()
main = do
putStrLn $ toTable [[1,2,3],[4,5,6],[7,8,9]]
return ()
The command runhaskell test.hs will now print
<table><tr><td>1</td><td>2</td><td>3</td></tr><tr><td>4</td><td>5</td><td>6</td></tr><tr><td>7</td><td>8</td><td>9</td></tr></table>
Explanation of the code
insideTag encapsulates content inside a html tag:
ghci> let insideTag tag content = "<" ++ tag ++ ">" ++ content ++ "</" ++ tag ++ ">"
ghci> insideTag "h1" "hello world"
"<h1>hello world</h1>"
map (concatMap (insideTag "td" . show)) list encapsulate the inner elements into <td> tags and concatenate them:
ghci> map (concatMap (insideTag "td" . show)) [[1,2], [3,4]]
["<td>1</td><td>2</td>","<td>3</td><td>4</td>"]
The same can be done for the outer list:
ghci> concatMap (insideTag "tr") ["<td>1</td><td>2</td>","<td>3</td><td>4</td>"]
"<tr><td>1</td><td>2</td></tr><tr><td>3</td><td>4</td></tr>"
The last string only has to be encapsulate into a <table> tag:
ghci> insideTag "table" "<tr><td>1</td><td>2</td></tr><tr><td>3</td><td>4</td></tr>"
"<table><tr><td>1</td><td>2</td></tr><tr><td>3</td><td>4</td></tr></table>"
Words of warning
The above code uses the normal [Char] type for strings which is not memory efficient. So I recommend that you use Data.Text if you deal with big tables (toTable remains the same, you just have to change show to pack . show; insideTag has to reimplemented for Data.Text).
There is also no HTML escaping for the table content!!! So the above code is vulnerable to XSS attacts. So do not use the above code, if the produced HTML shall be included in a website (especially if the website user has an influence on the table content)!
I have some html pages with numbers of verses like:
verses 2-5
verses 11-15
verses 21-23
I need to add for each number a code before the word "verses"
to be
<a name="2"></a><a name="3"></a><a name="4"></a><a name="5"></a>verses 2-5
etc.
So it takes the range of the numbers given, and before the beginning it adds:
<a name=""></a>
for each number in the range..
I use notepad++ to search and replace.
You're going to need a script to do this. I whipped up a simple Ruby script to do it. Used it on your sample text, got your output. Just download Ruby, paste this into a file in the directory of that text, and replace the verses.txt line with whatever your file name is. Then run it from the command line like: ruby ./script.rb
d = File.read('./verses.txt')
c = d[0..d.length]
c.scan(/(verses\s+\d+-\d+)/) do |n|
n.each do |a|
a.scan(/(\d+-\d+)/) do |nums|
z = nums.to_s.split(/-/)
st=''
in1 = z[0].gsub(/\["/, '').to_i
in2 = z[1].chomp("\"]").to_i
(in1..in2).each do |index|
st += "<a name=\"#{index}\"></a>"
end
b = st + a;
d.gsub!(a, b)
end
end
end
puts d
f = File.new('verses2.txt', "w")
f.write(d)
Per your request, here is a modification that will overwrite the opened file and run on all files in a directory. For ease, I won't do directory entry, so place the script in the directory of all the files to run it. Here goes:
Dir.entries('.').each do |entry|
entry.scan(/.*.html/) do
|fn|
d = File.read('./' + fn.to_s)
c = d[0..d.length]
c.scan(/(verses\s+\d+-\d+)/) do |n|
n.each do |a|
a.scan(/(\d+-\d+)/) do |nums|
z = nums.to_s.split(/-/)
st=''
in1 = z[0].gsub(/\["/, '').to_i
in2 = z[1].chomp("\"]").to_i
(in1..in2).each do |index|
st += "<a name=\"#{index}\"></a>"
end
b = st + a;
d.gsub!(a, b)
end
end
end
puts d
f = File.new('./' + fn.to_s, "w")
f.write(d)
end
end
I'll think about how to do the arabic encodings. This will run on all text files, if they have different extensions or have a similar name, let me know and I'll update the script.
This should fully work, just tested it. Let me know if there are issues.
You can do it for 2-digit verses 10 to 99 like this:
Search: verses (\d)(\d)-
Replace: <a name="$1">verses $1$2-</a>
For 3+ digit numbers, add another group for the extra digit(s) and treat similarly.
This extra complication is required because notepad++ doesn't support look-aheads AFAIK.