Cheatsheet

A short overview of common operators and constructs, useful for examples & projects in this guide. See the Reference Manual for the full list.

Stack Manipulation Operators

Stack before	Operator	Stack after	Description
$$any$$	`1`	$$any\ 1$$	Push element `1` onto the stack, value can be any literal or name
$$any$$	`pop`	$$-$$	Discard top element
$$a_{1}\ a_{2}$$	`exch`	$$a_{2}\ a_{1}$$	Exchange top two elements
$$a_{1}\ a_{2}$$	`dup`	$$a_{2}\ a_{1}$$	Duplicate top element
$$a_{1}\ \dots\ a_{n}\ n$$	`copy`	$$a_{1}\ \dots\ a_{n}\ a_{1}\ \dots\ a_{n}\ $$	Duplicate top $ n $ elements
$$a_{n}\ \dots\ a_{0}\ n$$	`index`	$$a_{n}\ \dots\ a_{0}\ a_{n}$$	Duplicate arbitrary element
$$a_{n-1}\ \dots\ a_{0}\ n\ j$$	`roll`	$$a_{(j-1)\ mod\ n}\ \dots\ a_{0}\ a_{n-1}\ \dots a_{j\ mod\ n}$$	Roll $ n $ elements up $ j $ times
$$a_{n}\ \dots\ a_{0}$$	`clear`	$$-$$	Discard all elements
$$a_{n}\ \dots\ a_{0}$$	`count`	$$a_{n}\ \dots\ a_{0}\ n$$	Count elements on stack

Stack before	Operator	Stack after	Description
$$n_{1}\ n_{2}$$	`add`	$$sum$$	$ n_{1} + n_{2} $
$$n_{1}\ n_{2}$$	`sub`	$$diff$$	$ n_{1} - n_{2} $
$$n_{1}\ n_{2}$$	`mul`	$$product$$	$ n_{1} \times n_{2} $
$$n_{1}\ n_{2}$$	`div`	$$quotient$$	$ n_{1} \div n_{2} $
$$n$$	`neg`	$$-n$$	Negative of $ n $
$$n$$	`sqrt`	$$\sqrt{n}$$	Square root of $ n $
$$a$$	`cos`	$$\cos{a}$$	Cosine of $ a $ degrees
$$a$$	`sin`	$$\sin{a}$$	Sine of $ a $ degrees
$$-$$	`rand`	$$n$$	Pseudo-random integer

Stack before	Operator	Stack after	Description
$$-$$	`[`	$$mark$$	Start array construction
$$mark\ obj_{0}\ \dots\ obj_{n-1}$$	`]`	$$array$$	End array construction
$$array$$	`length`	$$int$$	Number of elements in $ array $
$$array\ proc$$	`forall`	$$-$$	Execute $ proc $ for each element of $ array $

Stack before	Operator	Stack after	Description
$$n$$	`dict`	$$dict$$	Create dictionary with capacity $ n $
$$-$$	`<<`	$$mark$$	Start dictionary construction
$$mark\ key_{1}\ value_{1}\ \dots\ key_{n}\ value_{n}$$	`>>`	$$dict$$	End dictionary construction
$$dict$$	`length`	$$int$$	Number of entries in $ dict $
$$dict$$	`begin`	$$-$$	Push $ dict $ on dictionary stack
$$-$$	`end`	$$-$$	Pop current dictionary off dictionary stack
$$/key\ value$$	`def`	$$-$$	Associate $ key $ with $ value $ in current dictionary

Stack before	Operator	Stack after	Description
$$n_{1}\ n_{2}$$	`eq`	$$bool$$	Test equal
$$n_{1}\ n_{2}$$	`ne`	$$bool$$	Test not equal
$$n_{1}\ n_{2}$$	`ge`	$$bool$$	Test greater than or equal
$$n_{1}\ n_{2}$$	`gt`	$$bool$$	Test greater than
$$n_{1}\ n_{2}$$	`le`	$$bool$$	Test less than or equal
$$n_{1}\ n_{2}$$	`gt`	$$bool$$	Test less than
$$-$$	`true`	$$\text{true}$$	Literal value $ \text{true} $
$$-$$	`false`	$$\text{false}$$	Literal value $ \text{false} $

Stack before	Operator	Stack after	Description
$$any$$	`exec`	$$-$$	Execute arbitrary object
$$bool\ proc$$	$$if$$	$$-$$	Execute $ proc $ if $ bool $ is true
$$bool\ proc_{1}\ proc_{2}$$	$$ifelse$$	$$-$$	Execute $ proc_{1} $ if $ bool $ is true, $ proc_{2} $ if false
$$init\ inc\ limit\ proc$$	$$for$$	$$-$$	Execute $ proc $ with values from $ init $ by steps of $ inc $ to $ limit $
$$n\ proc$$	$$repeat$$	$$-$$	Execute $ proc $ $ n $ times
$$proc$$	$$loop$$	$$-$$	Execute $ proc $ an indefinite number of times
$$-$$	$$exit$$	$$-$$	Exit innermost active loop

Stack before	Operator	Stack after	Description
$$-$$	`gsave`	$$-$$	Push graphics state
$$-$$	`grestore`	$$-$$	Pop graphics state
$$num$$	`setlinewidth`	$$-$$	Set line width
$$-$$	`currentlinewidth`	$$int$$	Current line width
$$int$$	`setlinecap`	$$-$$	Set shape of line ends for stroke (`0 = butt`, `1 = round`, `2 = square`)
$$-$$	`currentlinecap`	$$int$$	Current line cap
$$int$$	setlinejoin	$$-$$	Set shape of corners for stroke (0 = miter, 1 = round, 2 = bevel)
$$-$$	`currentlinejoin`	$$int$$	Current line join
$$num$$	`setgray`	$$-$$	Set color to specified gray value (0 = black, 1 = white)

Stack before	Operator	Stack after	Description
$$t_{x}\ t_{y}$$	`translate`	$$-$$	Translate user space by $ (t_{x}, t_{y}) $
$$s_{x}\ s_{y}$$	`scale`	$$-$$	Translate user space by $ (s_{x}, s_{y}) $
$$a$$	`rotate`	$$-$$	Rotate user space by $ a $ degrees

Stack before	Operator	Stack after	Description
$$-$$	`newpath`	$$-$$	Initialize current path to be empty
$$-$$	`currentpoint`	$$x y$$	Return current point coordinates
$$x\ y$$	`moveto`	$$-$$	Set current point to $ (x, y) $
$$dx\ dy$$	`rmoveto`	$$-$$	Perform relative `moveto`
$$x\ y$$	`lineto`	$$-$$	Append straight line to $ (x, y) $
$$dx\ dy$$	`rmoveto`	$$-$$	Perform relative `lineto`
$$x\ y\ r\ a_{1}\ a_{2}$$	`arc`	$$-$$	Append counterclockwise arc, with $ (x, y) $ as the center for a radius of $ r $ from angle $ a_{1} $ to angle $ a_{2} $
$$x\ y\ r\ a_{1}\ a_{2}$$	`arcn`	$$-$$	Append clockwise arc
$$x_{1}\ y_{1}\ x_{2}\ y_{2}\ x_{3}\ y_{3}$$	`curveto`	$$-$$	Append Bézier cubic section
$$-$$	`closepath`	$$-$$	Connect subpath back to its starting point

Stack before	Operator	Stack after	Description
$$-$$	`erasepage`	$$-$$	Paint current page white
$$-$$	`stroke`	$$-$$	Draw line along current path
$$-$$	`fill`	$$-$$	Fill current path with current color

Stack before	Operator	Stack after	Description
$$any_{1}\ \dots\ any_{n}$$	`stack`	$$any_{1}\ \dots\ any_{n}$$	Print stack nondestructively
$$-$$	`showpage`	$$-$$	Transmit and reset current page

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Creates a dictionary of key-value pairs from the given list, puts the dictionary on the dictionary stack, and later pops it off the stack again.

<</foo 1 /bar 2 /baz 3>> begin
    ...
end

Creates a new procedure named proc:

/proc {
    ...
} def

Creates a new procedure named proc, which expects 3 operands on the stack: x y z.

/proc { % x y z
    [/x /y /z] dup length dict begin { exch def } forall
        ...
    end
} def