Visual representation of binary trees in Elm

VisualBinaryTree.elm

import Text (asText)
import Graphics.Collage (collage, toForm, filled, circle, move, scale, Form)
import Graphics.Element (Element)
import Color (red)
import List (map, (::), reverse)

type BinaryTree a = Nil | Node (BinaryTree a) a (BinaryTree a)

insert : comparable -> BinaryTree comparable -> BinaryTree comparable
insert node tree = 
  case tree of 
    Nil -> Node Nil node Nil
    Node left leaf right ->
      if  | leaf == node -> Node left leaf right  
          | leaf <  node -> Node left leaf (insert node right)
          | leaf >  node -> Node (insert node left) leaf right
          
          
push : BinaryTree comparable -> comparable -> BinaryTree comparable
push = flip insert 

isEmpty : BinaryTree a -> Bool
isEmpty tree = 
  case tree of 
    Nil -> True
    _ -> False
    
    
contains : comparable -> BinaryTree comparable -> Bool
contains node tree = 
  case tree of 
    Nil -> False
    Node left leaf right ->
      if | leaf == node -> True
         | leaf <  node -> contains leaf left
         | leaf >  node -> contains leaf right
         


drawTree : BinaryTree a -> List Form
drawTree tree = 
  case tree of 
    Nil -> []
    Node left leaf right ->
      [filled red (circle 30), scale 2 <| toForm <| asText leaf] ++
      map (move (-40,-60)) (drawTree left) ++
      map (move (40, -60)) (drawTree right)


renderTree : BinaryTree a -> Element
renderTree = collage 600 600 << map (move (0, 260)) << drawTree


t1 = Nil
t2 = insert 2 t1
t3 = insert 3 t2
t4 = insert 1 t3


tree : BinaryTree Int
tree = 
  Nil `push` 5
      `push` 6
      `push` 4
      `push` 3
      `push` 1
      `push` 8
      `push` 0
      `push` 7
      `push` 2
      `push` 9
      
fromList : List comparable -> BinaryTree comparable 
fromList list = 
  let reversedList = reverse list
      innerFromList l = 
        case l of 
          [] -> Nil
          x :: xs -> insert x (innerFromList xs)
  in innerFromList reversedList
  
  
treeList = fromList [4,2,0,8,9,10,1,-1,23,8,9,7,11,13,-4,0,9, -2, -3]


main : Element
main = renderTree treeList

Updated for Elm 0.15.1:

import Graphics.Collage exposing (collage, toForm, filled, circle, move, scale, Form)
import Graphics.Element exposing (Element, show)
import Color exposing (red)
import List exposing (map, (::), reverse)

type BinaryTree a = Nil | Node (BinaryTree a) a (BinaryTree a)

insert : comparable -> BinaryTree comparable -> BinaryTree comparable
insert node tree = 
  case tree of 
    Nil -> Node Nil node Nil
    Node left leaf right ->
      if  | leaf == node -> Node left leaf right  
          | leaf <  node -> Node left leaf (insert node right)
          | leaf >  node -> Node (insert node left) leaf right


push : BinaryTree comparable -> comparable -> BinaryTree comparable
push = flip insert 

isEmpty : BinaryTree a -> Bool
isEmpty tree = 
  case tree of 
    Nil -> True
    _ -> False


contains : comparable -> BinaryTree comparable -> Bool
contains node tree = 
  case tree of 
    Nil -> False
    Node left leaf right ->
      if | leaf == node -> True
         | leaf <  node -> contains leaf left
         | leaf >  node -> contains leaf right



drawTree : BinaryTree a -> List Form
drawTree tree = 
  case tree of 
    Nil -> []
    Node left leaf right ->
      [filled red (circle 30), scale 2 <| toForm <| show leaf] ++
      map (move (-40,-60)) (drawTree left) ++
      map (move (40, -60)) (drawTree right)


renderTree : BinaryTree a -> Element
renderTree = collage 600 600 << map (move (0, 260)) << drawTree


t1 = Nil
t2 = insert 2 t1
t3 = insert 3 t2
t4 = insert 1 t3


tree : BinaryTree Int
tree = 
  Nil `push` 5
      `push` 6
      `push` 4
      `push` 3
      `push` 1
      `push` 8
      `push` 0
      `push` 7
      `push` 2
      `push` 9

fromList : List comparable -> BinaryTree comparable 
fromList list = 
  let reversedList = reverse list
      innerFromList l = 
        case l of 
          [] -> Nil
          x :: xs -> insert x (innerFromList xs)
  in innerFromList reversedList


treeList = fromList [4,2,0,8,9,10,1,-1,23,8,9,7,11,13,-4,0,9, -2, -3]


main : Element
main = renderTree treeList