On 2008-02-15, Cale Gibbard
-- | The 'select' function takes a list and produces a list of pairs -- consisting of an element of the list together with a list of the -- remaining elements. select :: [a] -> [(a,[a])] select [] = [] select (x:xs) = (x,xs) : [(y,x:ys) | (y,ys) <- select xs]
A couple tounge-in-cheek suggestions: "banishments" -- all possible ways a society can divide itself up into one banished person, and the rest of society. Or perhaps "hermits".
-- | The 'selectSplit' function takes a list and produces a list of -- triples consisting of a prefix of the list, the element after it, -- and the remainder of the list. selectSplit :: [a] -> [([a],a,[a])] selectSplit [] = [] selectSplit (x:xs) = ([],x,xs) : [(x:lys,y,rys) | (lys,y,rys) <- selectSplit xs]
I kind of want to call this "positionalPivots", because of the "pivoting element" used in dividing everything up into elements less than, and greater than a particular one. This is all possible choices, but it's using positional order, not comparison order to do this partioning. But I actually don't really see much utility in either of these. Do you have some examples of use, and how they're a commonly abstracted pattern that deserves using up namespace because of the utility of a common vocabulary? -- Aaron Denney -><-