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Haskell is an advanced purely functional programming language. An open source product of more than twenty years of cutting edge research, it allows rapid development of robust, concise, correct software. With strong support for integration with other languages, built-in concurrency and parallelism, debuggers, profilers, rich libraries and an active community, Haskell makes it easier to produce flexible, maintainable high-quality software.
The function ++ concatenates (i.e., appends) two lists.
Prelude> :t (++) (++) :: [a] -> [a] -> [a] Prelude> ['f','u'] ++ "bar" "fubar"Define +++ which takes two lists, each possibly infinite, and returns a list which contains elements of the lists it is given, in the same order they appeared, but interleaved in such a way that any element that appears in either argument ultimately appears in the result.
Define cantor :: [[a]] -> [a] which similarly takes a (possibly infinite) list of (possibly infinite) lists and interleaves them in such a way that all elements in any of the lists in the input list appear at some point in the result list.
(my solution)(+++) :: [a] -> [a] -> [a] cantor :: [[a]] -> [a]
Define depthFirst and breadthFirst with
which traverse a tree giving the elements of the tree as a list, in either depth-first or breadth-first order. Example:data Tree a = Empty | Node a (Tree a) (Tree a) deriving Show depthFirst :: Tree a -> [a] breadthFirst :: Tree a -> [a]
(my solution 1 or 2)*Main> :load tre.hs [1 of 1] Compiling Main ( tre.hs, interpreted ) Ok, modules loaded: Main. *Main> depthFirst (Node 1 (Node 2 Empty (Node 3 Empty Empty)) (Node 4 Empty Empty)) [1,2,3,4] *Main> breadthFirst (Node 1 (Node 2 Empty (Node 3 Empty Empty)) (Node 4 Empty Empty)) [1,2,4,3]
Non-Monadic Warmup: Define sum2n :: Integer -> Int which calculate the sum of the digits of 2n, where n is its argument. Eg,
Prelude> :l h2.hs *Main> sum2n 1000000 1351546Make your definition as elegant and concise as possible. Extra kudos if you don't read my hints, enforced via honor system.
(b) Monadic Bliss!
Use a list monad to re-solve the SEND+MORE=MONEY cryptogram problem.
For efficiency, you can make a file foo.hs ending with
main = show (calcSolution)and compile it with
ghc -O9 -o foo foo.hsand then run the executable foo which will print the result. This can result in dramatic speedups.