diff --git a/interface.md b/interface.md
index 1850a14..7bcc46c 100644
--- a/interface.md
+++ b/interface.md
@@ -4,13 +4,13 @@
 ## Primitives
 
 - `step :: Karel -> Karel`<br>
-  Moves Karel one intersection forward
+  Moves Karel one intersection forward.
 - `turnLeft :: Karel -> Karel`<br>
-  Pivots Karel 90 degrees left
+  Pivots Karel 90 degrees left.
 - `pickBeeper :: Karel -> Karel`<br>
-  Takes a beeper from the current intersection and puts it in the beeper bag
+  Takes a beeper from the current intersection and puts it in the beeper bag.
 - `putBeeper :: Karel -> Karel`<br>
-  Takes a beeper from the beeper bag and puts it at the current intersection
+  Takes a beeper from the beeper bag and puts it at the current intersection.
 
 
 ## Sensors
@@ -18,11 +18,40 @@
 - `frontIsClear :: Karel -> Bool`<br>
   Returns `True` if there is no wall directly in front of Karel. Returns `False` if there is a wall.
 - `beepersPresent :: Karel -> Bool`<br>
-  Returns `True` if Karel is standing at an intersection that has a beeper, `False` otherwise
+  Returns `True` if Karel is standing at an intersection that has a beeper, `False` otherwise.
+- `facing :: Direction -> Karel -> Bool`<br>
+  Returns `True` if Karel is facing queried direction, `False` otherwise.
 - `facingNorth :: Karel -> Bool`<br>
-  Returns `True` if Karel is facing north, `False` otherwise
+  Returns `True` if Karel is facing north, `False` otherwise.
 - `beepersInBag :: Karel -> Bool`<br>
-  Returns `True` if there is at least one beeper in Karel's beeper bag, `False` if the beeper bag is empty
+  Returns `True` if there is at least one beeper in Karel's beeper bag, `False` if the beeper bag is empty.
+
+## Creating world
+
+- `worldWithDimensions :: Vector -> World`<br>
+  Takes a pair of integers, specifying dimensions of a world `(width, height)` and
+  returns new world.
+- `setBeepersAt :: Vector -> Int -> World -> World`<br>
+  Sets beepers at specified position, if beepers = 0 => removes them, negative count
+  or position not in the world results in error.
+- `addWallAt :: Vector -> Direction -> World -> World`<br>
+  Adds wall at specified position to specified direction, if position is not in the
+  world, results in error.
+- `removeWallAt :: Vector -> Direction -> World -> World`<br>
+  Removes wall at specified position to specified direction, if position is not in
+  the world, results in error.
+
+## Creating Karel
+
+- `defaultKarel :: World -> Karel`<br>
+  Creates Karel instance with a given world. Karel is defaultly placed at (1, 1),
+  facing East with no beepers in his bag.
+- `initialPosition :: Vector -> Karel -> Karel`<br>
+  Sets Karel's initial position, if position is out of the world, results in error.
+- `initialDirection :: Direction -> Karel -> Karel`<br>
+  Sets Karel's initial direction.
+- `initialBeepersInBag :: Int -> Karel -> Karel`<br>
+  Sets Karel's initial beepers in bag, if negative number is given, results in error.
 
 # Super Karel Language Reference
 
@@ -33,29 +62,31 @@ Super Karel is an extension to the basic Karel the Karel library. Super Karel is
 - `frontIsBlocked :: Karel -> Bool`<br>
   Returns `True` if there is a wall directly in front of Karel, `False` otherwise.
 - `leftIsClear :: Karel -> Bool`<br>
-  Returns `True` if there is no wall immediately to Karel's left, `False` if there is
+  Returns `True` if there is no wall immediately to Karel's left, `False` if there is.
 - `leftIsBlocked :: Karel -> Bool`<br>
-  Returns `True` if there is a wall immediately to Karel's left, `False` otherwise
+  Returns `True` if there is a wall immediately to Karel's left, `False` otherwise.
 - `rightIsClear :: Karel -> Bool`<br>
-  Returns `True` if there is no wall immediately to Karel's right, `False` if there is
+  Returns `True` if there is no wall immediately to Karel's right, `False` if there is.
 - `rightIsBlocked :: Karel -> Bool`<br>
-  Returns `True` if there is a wall immediately to Karel's right, `False` otherwise
+  Returns `True` if there is a wall immediately to Karel's right, `False` otherwise.
 - `no_beepers_present :: Karel -> Bool`<br>
-  Returns `True` if there is not beeper at the current intersection, `False` if there is a beeper at the current intersection
+  Returns `True` if there is not beeper at the current intersection, `False` if there is a beeper at the current intersection.
+- `notFacing :: Direction -> Karel -> Bool`<br>
+  Returns `True` if Karel is not facing queried direction, `False` if he is facing north.
 - `notFacingNorth :: Karel -> Bool`<br>
-  Returns `True` if Karel is not facing north, `False` if he is facing north
+  Returns `True` if Karel is not facing north, `False` if he is facing north.
 - `facingSouth :: Karel -> Bool`<br>
-  Returns `True` if Karel is facing south, `False` otherwise
+  Returns `True` if Karel is facing south, `False` otherwise.
 - `notFacingSouth :: Karel -> Bool`<br>
-  Returns `True` if Karel is not facing south, `False` if he is facing south
+  Returns `True` if Karel is not facing south, `False` if he is facing south.
 - `facingEast :: Karel -> Bool`<br>
-  Returns `True` if Karel is facing east, `False` otherwise
+  Returns `True` if Karel is facing east, `False` otherwise.
 - `notFacingEast :: Karel -> Bool`<br>
-  Returns `True` if Karel is not facing east, `False` if he is facing east
+  Returns `True` if Karel is not facing east, `False` if he is facing east.
 - `facingWest :: Karel -> Bool`<br>
-  Returns `True` if Karel is facing west, `False` otherwise
+  Returns `True` if Karel is facing west, `False` otherwise.
 - `notFacingWest :: Karel -> Bool`<br>
-  Returns `True` if Karel is not facing west, `False` if he is facing west
+  Returns `True` if Karel is not facing west, `False` if he is facing west.
 - `noBeepersInBag :: Karel -> Bool`<br>
-  Returns `True` if Karel's beeper bag is empty, `False` if there is at least one beeper in the beeper bag
+  Returns `True` if Karel's beeper bag is empty, `False` if there is at least one beeper in the beeper bag.