contiguousGroupBy

contiguousGroupBy.fs

let inline contiguousGroupBy (f:'a -> 'b) (xs:'a seq) : seq<'a list> = seq {
   use e = xs.GetEnumerator()
   let stop = ref (e.MoveNext() |> not)
   while not !stop do
      let lastval = ref (f e.Current)
      let list = 
         [
            while not !stop && !lastval = f e.Current do
               let cur = e.Current
               lastval := f cur
               yield cur
               stop := e.MoveNext() |> not
         ]
      yield list }

//Test
contiguousGroupBy (id) "Mississippi";;
val it : seq<char list> = seq [['M']; ['i']; ['s'; 's']; ['i']; ...]