Difference between revisions of "H-99: Ninety-Nine Haskell Problems"

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If you want to work on one of these, put your name in the block so we know someone's working on it. Then, change n in your block to the appropriate problem number, and fill in the <Problem description>,<example in lisp>,<example in Haskell>,<solution in haskell> and <description of implementation> fields.
 
If you want to work on one of these, put your name in the block so we know someone's working on it. Then, change n in your block to the appropriate problem number, and fill in the <Problem description>,<example in lisp>,<example in Haskell>,<solution in haskell> and <description of implementation> fields.
   
== Problem 1 ==
 
  +
These problems have been split into 10 parts, for ease of access:
   
(*) Find the last box of a list.
 
  +
Questions 1-10: [[99_questions/1_to_10]]
 
  +
Questions 11-20: [[99_questions/11_to_20]]
Example:
 
  +
Questions 21-30: [[99_questions/21_to_30]]
 
  +
Questions 31-40: [[99_questions/31_to_40]]
<pre>
 
  +
Questions 41-50: [[99_questions/41_to_50]]
* (my-last '(a b c d))
 
  +
Questions 51-60: [[99_questions/51_to_60]]
(D)
 
  +
Questions 61-70: [[99_questions/61_to_70]]
</pre>
 
  +
Questions 71-80: [[99_questions/71_to_80]]
 
  +
Questions 81-90: [[99_questions/81_to_90]]
Example in Haskell:
 
  +
Questions 91-100: [[99_questions/91_to_100]]
 
<haskell>
 
Prelude> last [1,2,3,4]
 
4
 
Prelude> last ['x','y','z']
 
'z'
 
</haskell>
 
 
Solution:
 
 
<haskell>
 
last :: [a] -> a
 
last [x] = x
 
last (_:xs) = last xs
 
</haskell>
 
 
This function is defined in Prelude.
 
 
== Problem 2 ==
 
 
(*) Find the last but one box of a list.
 
<pre>
 
Example:
 
* (my-but-last '(a b c d))
 
(C D)
 
</pre>
 
 
This can be done by dropping all but the last two elements of a list:
 
 
<haskell>
 
myButLast :: [a] -> [a]
 
myButLast list = drop ((length list) - 2) list
 
</haskell>
 
 
== Problem 3 ==
 
 
(*) Find the K'th element of a list.
 
The first element in the list is number 1.
 
<pre>
 
Example:
 
* (element-at '(a b c d e) 3)
 
C
 
</pre>
 
 
This is (almost) the infix operator !! in Prelude, which is defined as:
 
 
<haskell>
 
(!!) :: [a] -> Int -> a
 
(x:_) !! 0 = x
 
(_:xs) !! n = xs !! (n-1)
 
</haskell>
 
 
Except this doesn't quite work, because !! is zero-indexed, and element-at should be one-indexed. So:
 
 
<haskell>
 
elementAt :: [a] -> Int -> a
 
elementAt list i = list !! (i-1)
 
</haskell>
 
 
== Problem 4 ==
 
 
(*) Find the number of elements of a list.
 
 
This is "length" in Prelude, which is defined as:
 
 
<haskell>
 
length :: [a] -> Int
 
length [] = 0
 
length (_:l) = 1 + length l
 
</haskell>
 
 
== Problem 5 ==
 
 
(*) Reverse a list.
 
 
This is "reverse" in Prelude, which is defined as:
 
 
<haskell>
 
reverse :: [a] -> [a]
 
reverse = foldl (flip (:)) []
 
</haskell>
 
 
The standard definition is concise, but not very readable. Another way to define reverse is:
 
 
<haskell>
 
reverse :: [a] -> [a]
 
reverse [] = []
 
reverse (x:xs) = reverse xs ++ [x]
 
</haskell>
 
 
== Problem 6 ==
 
 
(*) Find out whether a list is a palindrome. A palindrome can be read forward or backward; e.g. (x a m a x).
 
 
This is trivial, because we can use reverse:
 
 
<haskell>
 
isPalindrome :: (Eq a) => [a] -> Bool
 
isPalindrome xs = xs == (reverse xs)
 
</haskell>
 
 
== Problem 7 ==
 
 
(**) Flatten a nested list structure.
 
 
Transform a list, possibly holding lists as elements into a `flat' list by replacing each list with its elements (recursively).
 
 
<pre>
 
Example:
 
* (my-flatten '(a (b (c d) e)))
 
(A B C D E)
 
</pre>
 
 
This is tricky, because lists in Haskell are homogeneous. [1, [2, [3, 4], 5]]
 
is a type error. We have to devise some way of represent a list that may (or
 
may not) be nested:
 
 
<haskell>
 
data NestedList a = Elem a | List [NestedList a]
 
 
flatten :: NestedList a -> [a]
 
flatten (Elem x) = [x]
 
flatten (List []) = []
 
flatten (List (x:xs)) = flatten x ++ flatten (List xs)
 
</haskell>
 
 
Our NestedList datatype is either a single element of some type (Elem a), or a
 
list of NestedLists of the same type. (List [NestedList a]). Let's try it out in ghci:
 
 
<pre>
 
*Main> flatten (Elem 5)
 
[5]
 
*Main> flatten (List [Elem 1, List [Elem 2, List [Elem 3, Elem 4], Elem 5]])
 
[1,2,3,4,5]
 
*Main> flatten (List [])
 
[]
 
</pre>
 
 
== Problem 8 ==
 
 
(**) Eliminate consecutive duplicates of list elements.
 
 
If a list contains repeated elements they should be replaced with a single copy of the element. The order of the elements should not be changed.
 
 
<pre>
 
Example:
 
* (compress '(a a a a b c c a a d e e e e))
 
(A B C A D E)
 
 
Example in Haskell:
 
*Main> compress ['a','a','a','a','b','c','c','a','a','d','e','e','e','e']
 
['a','b','c','a','d','e']
 
</pre>
 
 
Solution:
 
<haskell>
 
compress = map head . group
 
</haskell>
 
 
We simply group equal values together (group), then take the head of each.
 
 
== Problem 9 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 10 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 11 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 12 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 13 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 14 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 15 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 16 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 17 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 18 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 19 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 20 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 21 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 22 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 23 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 24 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 25 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 26 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 27 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 28 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 29 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 30 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 31 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 32 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 33 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 34 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 35 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 36 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 37 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 38 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 39 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 40 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 41 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 42 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 43 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 44 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 45 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 46 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 47 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 48 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 49 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 50 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 51 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 52 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 53 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 54 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 55 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 56 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 57 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 58 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 59 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 60 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 61 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 62 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 63 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 64 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 65 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 66 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 67 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 68 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 69 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 70 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 71 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 72 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 73 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 74 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 75 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 76 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 77 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 78 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 79 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 80 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 81 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 82 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 83 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 84 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 85 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 86 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 87 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 88 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 89 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 90 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 91 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 92 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 93 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 94 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 95 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 96 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 97 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 98 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
== Problem 99 ==
 
 
<Problem description>
 
 
<pre>
 
Example:
 
<example in lisp>
 
 
Example in Haskell:
 
<example in Haskell>
 
</pre>
 
 
Solution:
 
<haskell>
 
<solution in haskell>
 
</haskell>
 
 
<description of implementation>
 
 
 
[[Category:Tutorials]]
 
[[Category:Tutorials]]

Revision as of 06:53, 12 December 2006


These are Haskell translations of Ninety Nine Lisp Problems.

If you want to work on one of these, put your name in the block so we know someone's working on it. Then, change n in your block to the appropriate problem number, and fill in the <Problem description>,<example in lisp>,<example in Haskell>,<solution in haskell> and <description of implementation> fields.

These problems have been split into 10 parts, for ease of access:

Questions 1-10: 99_questions/1_to_10 Questions 11-20: 99_questions/11_to_20 Questions 21-30: 99_questions/21_to_30 Questions 31-40: 99_questions/31_to_40 Questions 41-50: 99_questions/41_to_50 Questions 51-60: 99_questions/51_to_60 Questions 61-70: 99_questions/61_to_70 Questions 71-80: 99_questions/71_to_80 Questions 81-90: 99_questions/81_to_90 Questions 91-100: 99_questions/91_to_100