Table of Contents

• 1. repeat
  • 1.1. Syntax
  • 1.2. Stack Effects
  • 1.3. Description
  • 1.4. PostScript Level
  • 1.5. Examples
  • 1.6. Common Use Cases
    • 1.6.1. Simple Drawing
    • 1.6.2. Buffer Initialization
    • 1.6.3. Pattern Generation
  • 1.7. Common Pitfalls
  • 1.8. Error Conditions
  • 1.9. Implementation Notes
  • 1.10. Comparison
  • 1.11. See Also

1. repeat

Executes a procedure a specified number of times.

1.1. Syntax

int proc repeat → –

1.2. Stack Effects

Table 1. Before

Level	Object
1	int (non-negative integer)
0	proc (procedure to execute)

Table 2. After

Level	Object
(varies)	Results from procedure executions

1.3. Description

repeat executes proc exactly int times, where int must be a non-negative integer.

The operator removes both operands before executing proc for the first time. If int is 0, proc is not executed at all.

If proc executes exit, the loop terminates prematurely.

1.4. PostScript Level

Level 1 and later

1.5. Examples

Simple repetition

4 { (abc) } repeat
% Stack: (abc) (abc) (abc) (abc)

With side effects

10 { (.) print } repeat
% Prints: ..........

Zero repetitions

mark 0 { (won't happen) } repeat
% Stack: mark (procedure never executed)

Removing values

1 2 3 4
3 { pop } repeat
% Stack: 1 (removed top 3 values)

1.6. Common Use Cases

1.6.1. Simple Drawing

5 {
  0 0 moveto
  72 0 rlineto
  stroke
  0 10 translate
} repeat

1.6.2. Buffer Initialization

100 { 0 } repeat
100 array astore
% Array of 100 zeros

1.6.3. Pattern Generation

10 {
  gsave
    % Draw pattern element
    currentpoint translate
    drawElement
  grestore
  spacing 0 translate
} repeat

1.7. Common Pitfalls

Stack Accumulation - If proc pushes values without consuming them, they accumulate.

10 { 42 } repeat
% Stack has 10 copies of 42!

No Control Variable - Unlike for, repeat doesn’t provide iteration index.

5 { % No way to know which iteration } repeat

Use for if Index Needed - If you need to know the iteration number, use for instead:

0 1 4 { % Iteration index on stack } for

1.8. Error Conditions

Error	Condition
[rangecheck]	int is negative
[stackunderflow]	Fewer than 2 operands on stack
[typecheck]	int not integer, or proc not procedure

1.9. Implementation Notes

• Efficient for simple fixed repetition

• No control variable overhead

• Very fast for small counts

• Procedure executed in current context

1.10. Comparison

Use Case	Operator	Reason
Need iteration index	for	Provides control variable
Fixed count, no index	repeat	Simpler, faster
Conditional termination	loop	Exit when condition met
Iterate collection	forall	Works with arrays/strings

1.11. See Also

• for - Loop with control variable

• loop - Indefinite loop

• exit - Exit loop early

• forall - Iterate collections