Data.String - purescript-strings - Pursuit (original) (raw)

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Re-exports from Data.String.CodePoints

#uncons Source

uncons :: String -> Maybe { head :: CodePoint, tail :: String }

Returns a record with the first code point and the remaining code points of the string. Returns Nothing if the string is empty. Operates in constant space and time.

>>> uncons "𝐀𝐀 c 𝐀"
Just { head: CodePoint 0x1D400, tail: "𝐀 c 𝐀" }
>>> uncons ""
Nothing

#toCodePointArray Source

toCodePointArray :: String -> Array CodePoint

Creates an array of code points from a string. Operates in space and time linear to the length of the string.

>>> codePointArray = toCodePointArray "b 𝐀𝐀"
>>> codePointArray
[CodePoint 0x62, CodePoint 0x20, CodePoint 0x1D400, CodePoint 0x1D400]
>>> map singleton codePointArray
["b", " ", "𝐀", "𝐀"]

#takeWhile Source

takeWhile :: (CodePoint -> Boolean) -> String -> String

Returns a string containing the leading sequence of code points which all match the given predicate from the string. Operates in constant space and in time linear to the length of the string.

>>> takeWhile (\c -> fromEnum c == 0x1D400) "𝐀𝐀 b c 𝐀"
"𝐀𝐀"

#take Source

take :: Int -> String -> String

Returns a string containing the given number of code points from the beginning of the given string. If the string does not have that many code points, returns the empty string. Operates in constant space and in time linear to the given number.

>>> take 3 "b 𝐀𝐀 c 𝐀"
"b 𝐀"
-- compare to Data.String:
>>> take 3 "b 𝐀𝐀 c 𝐀"
"b �"

#stripSuffix Source

stripSuffix :: Pattern -> String -> Maybe String

If the string ends with the given suffix, return the portion of the string left after removing it, as a Just value. Otherwise, returnNothing.

stripSuffix (Pattern ".exe") "psc.exe" == Just "psc"
stripSuffix (Pattern ".exe") "psc" == Nothing

#stripPrefix Source

stripPrefix :: Pattern -> String -> Maybe String

If the string starts with the given prefix, return the portion of the string left after removing it, as a Just value. Otherwise, return Nothing.

stripPrefix (Pattern "http:") "http://purescript.org" == Just "//purescript.org"
stripPrefix (Pattern "http:") "https://purescript.org" == Nothing

#splitAt Source

splitAt :: Int -> String -> { after :: String, before :: String }

Splits a string into two substrings, where before contains the code points up to (but not including) the given index, and after contains the rest of the string, from that index on.

>>> splitAt 3 "b 𝐀𝐀 c 𝐀"
{ before: "b 𝐀", after: "𝐀 c 𝐀" }

Thus the length of (splitAt i s).before will equal either i orlength s, if that is shorter. (Or if i is negative the length will be 0.)

In code:

length (splitAt i s).before == min (max i 0) (length s)
(splitAt i s).before <> (splitAt i s).after == s
splitAt i s == {before: take i s, after: drop i s}

#singleton Source

singleton :: CodePoint -> String

Creates a string containing just the given code point. Operates in constant space and time.

>>> map singleton (toEnum 0x1D400)
Just "𝐀"

#length Source

length :: String -> Int

Returns the number of code points in the string. Operates in constant space and in time linear to the length of the string.

>>> length "b 𝐀𝐀 c 𝐀"
8
-- compare to Data.String:
>>> length "b 𝐀𝐀 c 𝐀"
11

#lastIndexOf' Source

lastIndexOf' :: Pattern -> Int -> String -> Maybe Int

Returns the number of code points preceding the first match of the given pattern in the string. Pattern matches following the given index will be ignored.

Giving a negative index is equivalent to giving 0 and giving an index greater than the number of code points in the string is equivalent to searching in the whole string.

Returns Nothing when no matches are found.

>>> lastIndexOf' (Pattern "𝐀") (-1) "b 𝐀𝐀 c 𝐀"
Nothing
>>> lastIndexOf' (Pattern "𝐀") 0 "b 𝐀𝐀 c 𝐀"
Nothing
>>> lastIndexOf' (Pattern "𝐀") 5 "b 𝐀𝐀 c 𝐀"
Just 3
>>> lastIndexOf' (Pattern "𝐀") 8 "b 𝐀𝐀 c 𝐀"
Just 7
>>> lastIndexOf' (Pattern "o") 5 "b 𝐀𝐀 c 𝐀"
Nothing

#lastIndexOf Source

lastIndexOf :: Pattern -> String -> Maybe Int

Returns the number of code points preceding the last match of the given pattern in the string. Returns Nothing when no matches are found.

>>> lastIndexOf (Pattern "𝐀") "b 𝐀𝐀 c 𝐀"
Just 7
>>> lastIndexOf (Pattern "o") "b 𝐀𝐀 c 𝐀"
Nothing

#indexOf' Source

indexOf' :: Pattern -> Int -> String -> Maybe Int

Returns the number of code points preceding the first match of the given pattern in the string. Pattern matches preceding the given index will be ignored. Returns Nothing when no matches are found.

>>> indexOf' (Pattern "𝐀") 4 "b 𝐀𝐀 c 𝐀"
Just 7
>>> indexOf' (Pattern "o") 4 "b 𝐀𝐀 c 𝐀"
Nothing

#indexOf Source

indexOf :: Pattern -> String -> Maybe Int

Returns the number of code points preceding the first match of the given pattern in the string. Returns Nothing when no matches are found.

>>> indexOf (Pattern "𝐀") "b 𝐀𝐀 c 𝐀"
Just 2
>>> indexOf (Pattern "o") "b 𝐀𝐀 c 𝐀"
Nothing

#fromCodePointArray Source

fromCodePointArray :: Array CodePoint -> String

Creates a string from an array of code points. Operates in space and time linear to the length of the array.

>>> codePointArray = toCodePointArray "c 𝐀"
>>> codePointArray
[CodePoint 0x63, CodePoint 0x20, CodePoint 0x1D400]
>>> fromCodePointArray codePointArray
"c 𝐀"

#dropWhile Source

dropWhile :: (CodePoint -> Boolean) -> String -> String

Drops the leading sequence of code points which all match the given predicate from the string. Operates in constant space and in time linear to the length of the string.

>>> dropWhile (\c -> fromEnum c == 0x1D400) "𝐀𝐀 b c 𝐀"
" b c 𝐀"

#drop Source

drop :: Int -> String -> String

Drops the given number of code points from the beginning of the string. If the string does not have that many code points, returns the empty string. Operates in constant space and in time linear to the given number.

>>> drop 5 "𝐀𝐀 b c"
"c"
-- compared to Data.String:
>>> drop 5 "𝐀𝐀 b c"
"b c" -- because "𝐀" occupies 2 code units

#countPrefix Source

countPrefix :: (CodePoint -> Boolean) -> String -> Int

Returns the number of code points in the leading sequence of code points which all match the given predicate. Operates in constant space and in time linear to the length of the string.

>>> countPrefix (\c -> fromEnum c == 0x1D400) "𝐀𝐀 b c 𝐀"
2

#contains Source

contains :: Pattern -> String -> Boolean

Checks whether the pattern appears in the given string.

contains (Pattern "needle") "haystack with needle" == true
contains (Pattern "needle") "haystack" == false

#codePointAt Source

codePointAt :: Int -> String -> Maybe CodePoint

Returns the first code point of the string after dropping the given number of code points from the beginning, if there is such a code point. Operates in constant space and in time linear to the given index.

>>> codePointAt 1 "𝐀𝐀𝐀𝐀"
Just (CodePoint 0x1D400) -- represents "𝐀"
-- compare to Data.String:
>>> charAt 1 "𝐀𝐀𝐀𝐀"
Just '�'

Re-exports from Data.String.Common

#split Source

split :: Pattern -> String -> Array String

Returns the substrings of the second string separated along occurences of the first string.

split (Pattern " ") "hello world" == ["hello", "world"]

#localeCompare Source

localeCompare :: String -> String -> Ordering

Compare two strings in a locale-aware fashion. This is in contrast to the Ord instance on String which treats strings as arrays of code units:

"ä" `localeCompare` "b" == LT
"ä" `compare` "b" == GT

#joinWith Source

joinWith :: String -> Array String -> String

Joins the strings in the array together, inserting the first argument as separator between them.

joinWith ", " ["apple", "banana", "orange"] == "apple, banana, orange"