2016 Update

Task/Palindrome-detection/00DESCRIPTION

@@ -1,37 +1,20 @@
-Write at least one function/method (or whatever it is called in your
-preferred language) to check if a sequence of characters (or bytes)
-is a [[wp:Palindrome|palindrome]] or not.
-The ''function'' must return a boolean value
-(or something that can be used as boolean value, like an integer).
+A [[wp:Palindrome|palindrome]] is a phrase which reads the same backward and forward.
 
-It is not mandatory to write also an example code that uses
-the ''function'', unless its usage could be not clear
-(e.g. the provided recursive C solution
-needs explanation on how to call the function).
+{{task heading}}
 
-It is not mandatory to handle properly encodings (see [[String length]]),
-i.e. it is admissible that the function does not recognize 'salàlas'
-as palindrome.
+Write a function or program that checks whether a given sequence of characters (or, if you prefer, bytes)
+is a palindrome.
 
-The function must not ignore spaces and punctuations.
-The compliance to the aforementioned, strict or not,
-requirements completes the task.
+'''''For extra credit:'''''
+* Support Unicode characters.
+* Write a second function (possibly as a wrapper to the first) which detects ''inexact'' palindromes, i.e. phrases that are palindromes if white-space and punctuation is ignored and case-insensitive comparison is used.
 
-'''Example'''<br>
-An example of a Latin palindrome is the sentence
-"''In girum imus nocte et consumimur igni''",
-roughly translated as: we walk around in the night and we are burnt by the fire (of love).
-To do your test with it, you must make it all the same case and strip spaces.
-
-'''Clarification'''<br>
-To remove some confusion expressed in the discussion tab:
-
-* To satisfy this task, the function should only identify exact palindromes; it should *not* strip spaces or punctuation or convert case.
-* You may additionally write a wrapper function to detect inexact palindromes, such as the Latin example in the task description, or simply do the conversion in the calling function of your test code.
-
-'''Notes'''<br>
+{{task heading|Hints}}
 * It might be useful for this task to know how to [[Reversing a string|reverse a string]].
 * This task's entries might also form the subjects of the task [[Test a function]].
 
-;Cf.
-* [[Semordnilap]]
+{{task heading|Related tasks}}
+
+{{Related tasks/Word plays}}
+
+<hr>

Task/Palindrome-detection/AppleScript/palindrome-detection.applescript

@@ -0,0 +1,73 @@
+use framework "Foundation"
+
+
+-- isPalindrome :: String -> Bool
+on isPalindrome(s)
+    s = intercalate("", reverse of characters of s)
+end isPalindrome
+
+
+
+-- TEST
+
+on run
+
+    isPalindrome(lowerCaseNoSpace("In girum imus nocte et consumimur igni"))
+
+    --> true
+
+end run
+
+-- lowerCaseNoSpace :: String -> String
+on lowerCaseNoSpace(s)
+    script notSpace
+        on lambda(s)
+            s is not space
+        end lambda
+    end script
+
+    intercalate("", filter(notSpace, characters of toLowerCase(s)))
+end lowerCaseNoSpace
+
+
+-- GENERIC LIBRARY FUNCTIONS
+
+-- toLowerCase :: String -> String
+on toLowerCase(str)
+    set ca to current application
+    ((ca's NSString's stringWithString:(str))'s ¬
+        lowercaseStringWithLocale:(ca's NSLocale's currentLocale())) as text
+end toLowerCase
+
+-- intercalate :: Text -> [Text] -> Text
+on intercalate(strText, lstText)
+    set {dlm, my text item delimiters} to {my text item delimiters, strText}
+    set strJoined to lstText as text
+    set my text item delimiters to dlm
+    return strJoined
+end intercalate
+
+-- filter :: (a -> Bool) -> [a] -> [a]
+on filter(f, xs)
+    tell mReturn(f)
+        set lst to {}
+        set lng to length of xs
+        repeat with i from 1 to lng
+            set v to item i of xs
+            if lambda(v, i, xs) then set end of lst to v
+        end repeat
+        return lst
+    end tell
+end filter
+
+-- Lift 2nd class handler function into 1st class script wrapper
+-- mReturn :: Handler -> Script
+on mReturn(f)
+    if class of f is script then
+        f
+    else
+        script
+            property lambda : f
+        end script
+    end if
+end mReturn

Task/Palindrome-detection/BASIC/palindrome-detection.basic

@@ -1,32 +1,80 @@
-DECLARE FUNCTION isPalindrome% (what AS STRING)
+' OPTION _EXPLICIT ' For QB64. In VB-DOS remove the underscore.
 
-DATA "My dog has fleas", "Madam, I'm Adam.", "1 on 1", "In girum imus nocte et consumimur igni"
+DIM txt$
 
-DIM L1 AS INTEGER, w AS STRING
-FOR L1 = 1 TO 4
-    READ w
-    IF isPalindrome(w) THEN
-        PRINT CHR$(34); w; CHR$(34); " is a palindrome"
-    ELSE
-        PRINT CHR$(34); w; CHR$(34); " is not a palindrome"
-    END IF
-NEXT
+' Palindrome
+CLS
+PRINT "This is a palindrome detector program."
+PRINT
+INPUT "Please, type a word or phrase: ", txt$
 
-FUNCTION isPalindrome% (what AS STRING)
-    DIM whatcopy AS STRING, chk AS STRING, tmp AS STRING * 1, L0 AS INTEGER
+IF IsPalindrome(txt$) THEN
+  PRINT "Is a palindrome."
+ELSE
+  PRINT "Is Not a palindrome."
+END IF
 
-    FOR L0 = 1 TO LEN(what)
-        tmp = UCASE$(MID$(what, L0, 1))
-        SELECT CASE tmp
-            CASE "A" TO "Z"
-                whatcopy = whatcopy + tmp
-                chk = tmp + chk
-            CASE "0" TO "9"
-                PRINT "Numbers are cheating! ("; CHR$(34); what; CHR$(34); ")"
-                isPalindrome = 0
-                EXIT FUNCTION
-        END SELECT
-    NEXT
+END
+
+
+FUNCTION IsPalindrome (AText$)
+  ' Var
+  DIM CleanTXT$, RvrsTXT$
+
+  CleanTXT$ = CleanText$(AText$)
+  RvrsTXT$ = RvrsText$(CleanTXT$)
+
+  IsPalindrome = (CleanTXT$ = RvrsTXT$)
+
+END FUNCTION
+
+FUNCTION CleanText$ (WhichText$)
+  ' Var
+  DIM i%, j%, c$, NewText$, CpyTxt$, AddIt%, SubsTXT$
+  CONST False = 0, True = NOT False
+
+  SubsTXT$ = "AIOUE"
+  CpyTxt$ = UCASE$(WhichText$)
+  j% = LEN(CpyTxt$)
+
+  FOR i% = 1 TO j%
+    c$ = MID$(CpyTxt$, i%, 1)
+
+    ' See if it is a letter. Includes Spanish letters.
+    SELECT CASE c$
+      CASE "A" TO "Z"
+        AddIt% = True
+      CASE " ", "¡", "¢", "£"
+        c$ = MID$(SubsTXT$, ASC(c$) - 159, 1)
+        AddIt% = True
+      CASE "‚"
+        c$ = "E"
+        AddIt% = True
+      CASE "¤"
+        c$ = "¥"
+        AddIt% = True
+      CASE ELSE
+        AddIt% = False
+    END SELECT
+
+    IF AddIt% THEN
+      NewText$ = NewText$ + c$
+    END IF
+  NEXT i%
+
+  CleanText$ = NewText$
+
+END FUNCTION
+
+FUNCTION RvrsText$ (WhichText$)
+  ' Var
+  DIM i%, c$, NewText$, j%
+
+  j% = LEN(WhichText$)
+  FOR i% = 1 TO j%
+    NewText$ = MID$(WhichText$, i%, 1) + NewText$
+  NEXT i%
+
+  RvrsText$ = NewText$
 
-    isPalindrome = ((whatcopy) = chk)
 END FUNCTION

Task/Palindrome-detection/COBOL/palindrome-detection.cobol

@@ -0,0 +1,19 @@
+       identification division.
+       function-id. palindromic-test.
+
+       data division.
+       linkage section.
+       01 test-text            pic x any length.
+       01 result               pic x.
+          88 palindromic       value high-value
+                               when set to false low-value.
+
+       procedure division using test-text returning result.
+
+       set palindromic to false
+       if test-text equal function reverse(test-text) then
+           set palindromic to true
+       end-if
+
+       goback.
+       end function palindromic-test.

Task/Palindrome-detection/Dart/palindrome-detection.dart

@@ -1,4 +1,4 @@
-bool isPolindrome(String s){
+bool isPalindrome(String s){
   for(int i = 0; i < s.length/2;i++){
     if(s[i] != s[(s.length-1) -i])
       return false;

Task/Palindrome-detection/Go/palindrome-detection-2.go

@@ -0,0 +1,10 @@
+func isPalindrome(s string) bool {
+	runes := []rune(s)
+	numRunes := len(runes) - 1
+	for i := 0; i < len(runes)/2; i++ {
+		if runes[i] != runes[numRunes-i] {
+			return false
+		}
+	}
+	return true
+}

Task/Palindrome-detection/Go/palindrome-detection-3.go

@@ -0,0 +1,10 @@
+func isPalindrome(s string) bool {
+	runes := []rune(s)
+	for len(runes) > 1 {
+		if runes[0] != runes[len(runes)-1] {
+			return false
+		}
+		runes = runes[1 : len(runes)-1]
+	}
+	return true
+}

Task/Palindrome-detection/JavaScript/palindrome-detection-3.js

@@ -0,0 +1,28 @@
+(function (strSample) {
+
+    // isPalindrome :: String -> Bool
+    let isPalindrome = s =>
+        s.split('')
+        .reverse()
+        .join('') === s;
+
+
+
+    // TESTING
+
+    // lowerCaseNoSpace :: String -> String
+    let lowerCaseNoSpace = s =>
+        concatMap(c => c !== ' ' ? [c.toLowerCase()] : [],
+            s.split(''))
+        .join(''),
+
+        // concatMap :: (a -> [b]) -> [a] -> [b]
+        concatMap = (f, xs) => [].concat.apply([], xs.map(f));
+
+
+    return isPalindrome(
+        lowerCaseNoSpace(strSample)
+    );
+
+
+})("In girum imus nocte et consumimur igni");

Task/Palindrome-detection/NewLISP/palindrome-detection.newlisp

@@ -1,4 +1,8 @@
 (define (palindrome? s)
-        (setq r s)
-        (reverse r) ; Reverse is destructive.
-        (= s r))
+    (setq r s)
+    (reverse r) ; Reverse is destructive.
+    (= s r))
+
+;; Make ‘reverse’ non-destructive and avoid a global variable
+(define (palindrome? s)
+    (= s (reverse (copy s))))

Task/Palindrome-detection/PowerShell/palindrome-detection-2.psh

@@ -0,0 +1,34 @@
+function Test-Palindrome
+{
+  <#
+    .SYNOPSIS
+        Tests if a string is a palindrome.
+    .DESCRIPTION
+        Tests if a string is a true palindrome or, optionally, an inexact palindrome.
+    .EXAMPLE
+        Test-Palindrome -Text "racecar"
+    .EXAMPLE
+        Test-Palindrome -Text '"Deliver desserts," demanded Nemesis, "emended, named, stressed, reviled."' -Inexact
+  #>
+    [CmdletBinding()]
+    [OutputType([bool])]
+    Param
+    (
+        # The string to test for palindrominity.
+        [Parameter(Mandatory=$true)]
+        [string]
+        $Text,
+
+        # When specified, detects an inexact palindrome.
+        [switch]
+        $Inexact
+    )
+
+    if ($Inexact)
+    {
+        # Strip all punctuation and spaces
+        $Text = [Regex]::Replace("$Text($7&","[^1-9a-zA-Z]","")
+    }
+
+    $Text -match "^(?'char'[a-z])+[a-z]?(?:\k'char'(?'-char'))+(?(char)(?!))$"
+}

Task/Palindrome-detection/PowerShell/palindrome-detection-3.psh

@@ -0,0 +1 @@
+Test-Palindrome -Text 'radar'

Task/Palindrome-detection/PowerShell/palindrome-detection-4.psh

@@ -0,0 +1 @@
+Test-Palindrome -Text "In girum imus nocte et consumimur igni."

Task/Palindrome-detection/PowerShell/palindrome-detection-5.psh

@@ -0,0 +1 @@
+Test-Palindrome -Text "In girum imus nocte et consumimur igni." -Inexact

Task/Palindrome-detection/Python/palindrome-detection-5.py

@@ -0,0 +1,28 @@
+def p_loop():
+  import re, string
+  re1=""       # Beginning of Regex
+  re2=""       # End of Regex
+  pal=raw_input("Please Enter a word or phrase: ")
+  pd = pal.replace(' ','')
+  for c in string.punctuation:
+     pd = pd.replace(c,"")
+  if pal == "" :
+    return -1
+  c=len(pd)   # Count of chars.
+  loops = (c+1)/2
+  for x in range(loops):
+    re1 = re1 + "(\w)"
+    if (c%2 == 1 and x == 0):
+       continue
+    p = loops - x
+    re2 = re2 + "\\" + str(p)
+  regex= re1+re2+"$"   # regex is like "(\w)(\w)(\w)\2\1$"
+  #print(regex)  # To test regex before re.search
+  m = re.search(r'^'+regex,pd,re.IGNORECASE)
+  if (m):
+     print("\n   "+'"'+pal+'"')
+     print("   is a Palindrome\n")
+     return 1
+  else:
+     print("Nope!")
+     return 0

Task/Palindrome-detection/Rust/palindrome-detection.rust

@@ -0,0 +1,19 @@
+fn is_palindrome(string: &str) -> bool {
+    string.chars().zip(string.chars().rev()).all(|(x, y)| x == y)
+}
+
+macro_rules! test {
+    ( $( $x:tt ),* ) => { $( println!("'{}': {}", $x, is_palindrome($x)); )* };
+}
+
+fn main() {
+    test!("",
+          "a",
+          "ada",
+          "adad",
+          "ingirumimusnocteetconsumimurigni",
+          "人人為我,我為人人",
+          "Я иду с мечем, судия",
+          "아들딸들아",
+          "The quick brown fox");
+}

Task/Palindrome-detection/Vala/palindrome-detection.vala

@@ -0,0 +1,9 @@
+bool is_palindrome (string str) {
+    var tmp = str.casefold ().replace (" ", "");
+    return tmp == tmp.reverse ();
+}
+
+int main (string[] args) {
+    print (is_palindrome (args[1]).to_string () + "\n");
+    return 0;
+}