lab.hs

mylen [] = 0

myhead (h:t) = h
myhead [] = error "nie mozna na pustej liscie" 

mytail (h:t) = t


infixl 6 +++
[] +++ y = y
(h:t) +++ y =	h:(t +++ y)

mytake 0 ls = []
mytake quantity [] = []
mytake quantity (h:t) = h: (mytake (quantity - 1) t)

inits [] = [[]]
inits (h:t) = [] : [ (h:x) | x <- inits t] 


partitions [] = [([], [])]
partitions ls = subpartitions 0 ls


-- operator : po lewej stronie ma mieć ELEMENT a po prawej LISTĘ ELEMENTÓW

subpartitions x ls =
  if x < length ls then
  	(take x ls, drop x ls) : subpartitions (x+1) ls
	else
		[(ls, [])]