Partial unicode friendly encoding.

This encodes as UTF16-LE (strictly), which is a pretty good guess.

Throws an EncodingException if encoding fails. If the input does not contain surrogate chars, you can use unsafeEncodeUtf.

Unsafe unicode friendly encoding.

Like encodeUtf, except it crashes when the input contains surrogate chars. For sanitized input, this can be useful.

This mimics the behavior of the base library when doing filesystem operations (usually filepaths), which does permissive UTF-16 encoding, where coding errors generate Chars in the surrogate range.

The reason this is in IO is because it unifies with the Posix counterpart, which does require IO. This is safe to unsafePerformIO/unsafeDupablePerformIO.

This mimics the behavior of the base library when doing string operations, which does permissive UTF-16 encoding, where coding errors generate Chars in the surrogate range.

The reason this is in IO is because it unifies with the Posix counterpart, which does require IO. This is safe to unsafePerformIO/unsafeDupablePerformIO.

Like 'encodeLE but not in IO.

encodeLE was designed to have a symmetric type signature on unix and windows, but morally the function has no IO effects on windows, so we provide this variant without breaking existing API.

On windows, encodeLE is equivalent to encodeFS.

This function does not exist on unix.

Since: 2.0.6

Constructs a platform string from a ByteString.

This ensures valid UCS-2LE. Note that this doesn't expand Word8 to Word16 on windows, so you may get invalid UTF-16.

Throws EncodingException on invalid UCS-2LE (although unlikely).

Constructs a platform string from a ShortByteString.

This ensures valid UCS-2LE. Note that this doesn't expand Word8 to Word16 on windows, so you may get invalid UTF-16.

Throws EncodingException on invalid UCS-2LE (although unlikely).

Since: 2.0.8

Pack a list of platform words to a platform string.

Note that using this in conjunction with unsafeFromChar to convert from [Char] to platform string is probably not what you want, because it will truncate unicode code points.

Partial unicode friendly decoding.

This decodes as UTF16-LE (strictly), which is a pretty good.

Throws a EncodingException if decoding fails.

Like decodeUtf, except this mimics the behavior of the base library when doing filesystem operations (usually filepaths), which does permissive UTF-16 encoding, where coding errors generate Chars in the surrogate range.

The reason this is in IO is because it unifies with the Posix counterpart, which does require IO. unsafePerformIO/unsafeDupablePerformIO are safe, however.

Like decodeUtf, except this mimics the behavior of the base library when doing filesystem operations, which does permissive UTF-16 encoding, where coding errors generate Chars in the surrogate range.

The reason this is in IO is because it unifies with the Posix counterpart, which does require IO. unsafePerformIO/unsafeDupablePerformIO are safe, however.

Unpack a platform string to a list of platform words.

Truncates to 2 octets.

Converts back to a unicode codepoint (total).

O(n) Append a byte to the end of a WindowsString

O(n) cons is analogous to (:) for lists.

O(1) Extract the last element of a WindowsString, which must be finite and non-empty. An exception will be thrown in the case of an empty WindowsString.

This is a partial function, consider using unsnoc instead.

O(n) Extract the elements after the head of a WindowsString, which must be non-empty. An exception will be thrown in the case of an empty WindowsString.

This is a partial function, consider using uncons instead.

O(n) Extract the head and tail of a WindowsString, returning Nothing if it is empty.

O(1) Extract the first element of a WindowsString, which must be non-empty. An exception will be thrown in the case of an empty WindowsString.

This is a partial function, consider using uncons instead.

O(n) Return all the elements of a WindowsString except the last one. An exception will be thrown in the case of an empty WindowsString.

This is a partial function, consider using unsnoc instead.

O(n) Extract the init and last of a WindowsString, returning Nothing if it is empty.

O(1). The empty WindowsString.

O(1) The length of a WindowsString.

This returns the number of code units (Word8 on unix and Word16 on windows), not bytes.

>>> length "abc"
3

Note: older versions of os-string return the length in bytes, rather than the length in code units. This will return the length in code units, regardless of the version of os-string. For checking the length in Bytes, use lengthBytes.

O(1) The length in bytes of a WindowsString.

If you want the number of code units, just use length instead.

O(n) map f xs is the WindowsString obtained by applying f to each element of xs.

O(n) reverse xs efficiently returns the elements of xs in reverse order.

O(n) The intercalate function takes a WindowsString and a list of WindowsStrings and concatenates the list after interspersing the first argument between each element of the list.

foldl, applied to a binary operator, a starting value (typically the left-identity of the operator), and a WindowsString, reduces the WindowsString using the binary operator, from left to right.

foldl' is like foldl, but strict in the accumulator.

foldl1 is a variant of foldl that has no starting value argument, and thus must be applied to non-empty WindowsStrings. An exception will be thrown in the case of an empty WindowsString.

foldl1' is like foldl1, but strict in the accumulator. An exception will be thrown in the case of an empty WindowsString.

foldr, applied to a binary operator, a starting value (typically the right-identity of the operator), and a WindowsString, reduces the WindowsString using the binary operator, from right to left.

foldr' is like foldr, but strict in the accumulator.

foldr1 is a variant of foldr that has no starting value argument, and thus must be applied to non-empty WindowsStrings An exception will be thrown in the case of an empty WindowsString.

foldr1' is a variant of foldr1, but is strict in the accumulator.

O(n) Applied to a predicate and a PLATFString, all determines if all elements of the WindowsString satisfy the predicate.

O(n) Applied to a predicate and a WindowsString, any determines if any element of the WindowsString satisfies the predicate.

O(n) replicate n x is a WindowsString of length n with x the value of every element. The following holds:

replicate w c = unfoldr w (\u -> Just (u,u)) c

O(n), where n is the length of the result. The unfoldr function is analogous to the List 'unfoldr'. unfoldr builds a WindowsString from a seed value. The function takes the element and returns Nothing if it is done producing the WindowsString or returns Just (a,b), in which case, a is the next byte in the string, and b is the seed value for further production.

This function is not efficient/safe. It will build a list of [Word8] and run the generator until it returns Nothing, otherwise recurse infinitely, then finally create a WindowsString.

If you know the maximum length, consider using unfoldrN.

Examples:

   unfoldr (\x -> if x <= 5 then Just (x, x + 1) else Nothing) 0
== pack [0, 1, 2, 3, 4, 5]

O(n) Like unfoldr, unfoldrN builds a WindowsString from a seed value. However, the length of the result is limited by the first argument to unfoldrN. This function is more efficient than unfoldr when the maximum length of the result is known.

The following equation relates unfoldrN and unfoldr:

fst (unfoldrN n f s) == take n (unfoldr f s)

O(n) take n, applied to a WindowsString xs, returns the prefix of xs of length n, or xs itself if n > length xs.

O(n) takeEnd n xs is equivalent to drop (length xs - n) xs. Takes n elements from end of bytestring.

>>> takeEnd 3 "abcdefg"
"efg"
>>> takeEnd 0 "abcdefg"
""
>>> takeEnd 4 "abc"
"abc"

Returns the longest (possibly empty) suffix of elements satisfying the predicate.

takeWhileEnd p is equivalent to reverse . takeWhile p . reverse.

Similar to takeWhile, returns the longest (possibly empty) prefix of elements satisfying the predicate.

O(n) drop n xs returns the suffix of xs after the first n elements, or empty if n > length xs.

O(n) dropEnd n xs is equivalent to take (length xs - n) xs. Drops n elements from end of bytestring.

>>> dropEnd 3 "abcdefg"
"abcd"
>>> dropEnd 0 "abcdefg"
"abcdefg"
>>> dropEnd 4 "abc"
""

Similar to dropWhileEnd, drops the longest (possibly empty) suffix of elements satisfying the predicate and returns the remainder.

dropWhileEnd p is equivalent to reverse . dropWhile p . reverse.

Similar to dropWhile, drops the longest (possibly empty) prefix of elements satisfying the predicate and returns the remainder.

Similar to break, returns the longest (possibly empty) prefix of elements which do not satisfy the predicate and the remainder of the string.

break p is equivalent to span (not . p) and to (takeWhile (not . p) &&& dropWhile (not . p)).

Returns the longest (possibly empty) suffix of elements which do not satisfy the predicate and the remainder of the string.

breakEnd p is equivalent to spanEnd (not . p) and to (takeWhileEnd (not . p) &&& dropWhileEnd (not . p)).

Similar to span, returns the longest (possibly empty) prefix of elements satisfying the predicate and the remainder of the string.

span p is equivalent to break (not . p) and to (takeWhile p &&& dropWhile p).

Returns the longest (possibly empty) suffix of elements satisfying the predicate and the remainder of the string.

spanEnd p is equivalent to breakEnd (not . p) and to (takeWhileEnd p &&& dropWhileEnd p).

We have

spanEnd (not . isSpace) "x y z" == ("x y ", "z")

and

spanEnd (not . isSpace) sbs
   ==
let (x, y) = span (not . isSpace) (reverse sbs) in (reverse y, reverse x)

O(n) splitAt n sbs is equivalent to (take n sbs, drop n sbs).

O(n) Break a WindowsString into pieces separated by the byte argument, consuming the delimiter. I.e.

split 10  "a\nb\nd\ne" == ["a","b","d","e"]   -- fromEnum '\n' == 10
split 97  "aXaXaXa"    == ["","X","X","X",""] -- fromEnum 'a' == 97
split 120 "x"          == ["",""]             -- fromEnum 'x' == 120
split undefined ""     == []                  -- and not [""]

and

intercalate [c] . split c == id
split == splitWith . (==)

O(n) Splits a WindowsString into components delimited by separators, where the predicate returns True for a separator element. The resulting components do not contain the separators. Two adjacent separators result in an empty component in the output. eg.

splitWith (==97) "aabbaca" == ["","","bb","c",""] -- fromEnum 'a' == 97
splitWith undefined ""     == []                  -- and not [""]

O(n) The stripSuffix function takes two OsStrings and returns Just the remainder of the second iff the first is its suffix, and otherwise Nothing.

O(n) The stripPrefix function takes two OsStrings and returns Just the remainder of the second iff the first is its prefix, and otherwise Nothing.

Check whether one string is a substring of another.

O(n) The isPrefixOf function takes two OsStrings and returns True

O(n) The isSuffixOf function takes two OsStrings and returns True iff the first is a suffix of the second.

The following holds:

isSuffixOf x y == reverse x `isPrefixOf` reverse y

Break a string on a substring, returning a pair of the part of the string prior to the match, and the rest of the string.

The following relationships hold:

break (== c) l == breakSubstring (singleton c) l

For example, to tokenise a string, dropping delimiters:

tokenise x y = h : if null t then [] else tokenise x (drop (length x) t)
    where (h,t) = breakSubstring x y

To skip to the first occurrence of a string:

snd (breakSubstring x y)

To take the parts of a string before a delimiter:

fst (breakSubstring x y)

Note that calling `breakSubstring x` does some preprocessing work, so you should avoid unnecessarily duplicating breakSubstring calls with the same pattern.

O(n) elem is the WindowsString membership predicate.

O(n) The find function takes a predicate and a WindowsString, and returns the first element in matching the predicate, or Nothing if there is no such element.

find f p = case findIndex f p of Just n -> Just (p ! n) ; _ -> Nothing

O(n) filter, applied to a predicate and a WindowsString, returns a WindowsString containing those characters that satisfy the predicate.

O(n) The partition function takes a predicate a WindowsString and returns the pair of OsStrings with elements which do and do not satisfy the predicate, respectively; i.e.,

partition p bs == (filter p sbs, filter (not . p) sbs)

O(1) WindowsString index (subscript) operator, starting from 0.

O(1) WindowsString index, starting from 0, that returns Just if:

0 <= n < length bs

O(1) WindowsString index, starting from 0, that returns Just if:

0 <= n < length bs

O(n) The elemIndex function returns the index of the first element in the given WindowsString which is equal to the query element, or Nothing if there is no such element.

O(n) The elemIndices function extends elemIndex, by returning the indices of all elements equal to the query element, in ascending order.

count returns the number of times its argument appears in the WindowsString

O(n) The findIndex function takes a predicate and a WindowsString and returns the index of the first element in the WindowsString satisfying the predicate.

O(n) The findIndices function extends findIndex, by returning the indices of all elements satisfying the predicate, in ascending order.