X
X
t y l r
let
c
=
λ
m , n
.
m ! /
(
n ! *
(
m - n
)
!
)
in
c
(
9 , 3
)
←
→
Move
Shift
+
←
→
Select
↑
↓
Pick Up
|
Put Down
Backspace
Remove
/
Restructure
Delete
Remove
/
Restructure
Construct
0
-
9
single-digit num
a
-
z
single-char var
+
-
*
/
plus
|
minus
|
times
|
div
,
!
Space
pair
|
factorial
|
application
(
)
parentheses
?
:
ifzero
\
=
lambda
|
let