Quick reference logo guide:

Stuff should work in lower or upper case.

Types:

WORDS:          FW BW ....
NUMBERS:        0, 0.1, 20
LISTS:          [1 2 3 5]
SYMBOLS:        "foo "bar
VARIABLES:      :foo :bar 
FUNCTION CALLS: COMMAND arg arg arg ...
                (COMMAND arg arg arg ...)

Supported Commands:

RESET           Clear the screen, move home.


Turtle Movement:

FORWARD n       Move the turtle forward n pixels
FW n    

BACKWARD n      Move the turtle backward n pixels

RIGHT n         Move the turtle left or right n degrees
RT n
LEFT n
LT n

SETX x          Set the co-ordinates of the turtle
SETY y
SETXY x y

HOME            Move the turtle to the home position


Drawing:

CLEARSCREEN     Clear the screen
CLEAR
CS

CIRCLE r        Draw a Circle of radius r around the turtle

ARC r d         Draw an arc of radius r for d degrees

PENUP           Lift the pen up and down
PU
PENDOWN
PD

COLOR [r g b]   Set the pen color

PENWIDTH w      Set the pen width


Text:

PRINT "foo          Prints "foo"
PR "foo
PRINT ["foo "bar]   Prints "foo bar"
PR ["foo "bar]

CLEARTEXT           Clears previously printed text
CT


Arithmetic:

1 + 2                   1 * 2
SUM 1 2                 PRODUCT 1 2
(SUM 1 2 3 ...)         (PRODUCT 1 2 3 ...)

1 - 2                   1 / 2
DIFFERENCE 1 2          DIVIDE 1 2

1 % 2
MOD 1 2

RANDOM n        Return a integer in [0,n)
RAND n

RERANDOM s      Set the random seed value
SRAND s


INT n
ROUND n
POWER e m
EXP n
LN n
LOG10 n



SIN, COS
RADSIN,RADCOS

ARCTAN
RADARCTAN



List Operators (experimental):
These functions may break silently at the moment.

FIRST, HEAD             Return the first item in a list
BUTFIRST, TAIL          Return the everything but the first item in a list
LAST                    Return the last item in a list
BUTLAST                 Return everything but the last item in a list

FPUT item list  Return a new list with item at the front
LPUT item list  Return a new list with item at the back

ITEM index list                 Retrieve the indexed item
SETITEM index list value        Set the indexed item

EMPTY? list     Return true if list is empty
EMPTYP list 

Logical and Comparison:

1 = 1
EQUAL? 1 1
EQUALP 1 1

1 < 2                1 <= 2
LESS? 1 2               LESSEQUAL? 1 2
LESSP 1 2               LESSEQUALP 1 2

2 > 1                2 > 1
GREATER? 2 1            GREATEREQUAL? 2 1
GREATERP 2 1            GREATEREQUALP 2 1

AND TRUE FALSE          OR FALSE TRUE

Conditionals:

IF COND [IF_TRUE] 
IF 2 > 1 [FW 100]

IFELSE COND [IF_TRUE] [IF_FALSE]
IFELSE 2 > 1 [FW 100 RT 90] [BW 100 LT 90]


Setting and getting:

Set x to 1:             make "x 1
Adding :n to :x         :n + :x
Setting :x to :n + :x   make "x :x + :n

Looping:

REPEAT n [COMMANDS ...]

STOP    - Stop the current Repeat or function.

OUTPUT f  - Return f.
OP f


Defining and Calling:

TO FOO :ARG1 :ARG2 BODY END

TO SQUARE :length 
REPEAT 4 [FW :length RT 90]
END

SQUARE :10

TO POLYGON :length :sides
REPEAT :sides [FW :length RT 360/:sides]
END

POLYGON 5 10

Note: Simple Tail recursion is supported.