CLI Reference

--step Mode

An interactive, educational debugger that walks through your algorithm one line at a time, showing live variable state at each step.

Usage

bash

pseudo run sort.pseudo --step

How It Works

When --step is active, the interpreter pauses before executing each statement and prints:

The current source line
The canonical type (ASSIGN, WHILE_LOOP, SWAP, etc.)
The condition value for loops and if statements
The full variable state at that moment
For swaps: the before and after state of the affected array

Step Output Examples

Assignment and loop

step output

═══ Step 1 ═══════════════════════════════════
  Line: "i = 0"
  Type: ASSIGN
  State: { i: 0 }

═══ Step 2 ═══════════════════════════════════
  Line: "while i < len(arr)"
  Type: WHILE_LOOP  cond = (i < 5) = TRUE
  State: { i: 0 }

[Press Enter to continue, q to quit]

Swap operation

step output - swap

═══ Step 7 ═══════════════════════════════════
  Line: "swap arr[j] and arr[j+1]"
  Type: SWAP
  Before: arr = [5, 3, 8]
  After:  arr = [3, 5, 8]
  State: { i: 0, j: 0 }

[Press Enter to continue, q to quit]

Controls

Key	Action
`Enter`	Advance to next step
`q` + Enter	Quit step mode, stop execution

Teaching Example

Step mode is ideal for teaching algorithms. Run a bubble sort step by step to watch every comparison and swap:

sort.pseudo

func bubbleSort(arr)
    for i from 0 to len(arr)
        for j from 0 to len(arr) - i - 1
            if arr[j] > arr[j+1]
                swap arr[j] and arr[j+1]
    return arr

bubbleSort([5, 2, 9, 1])

bash

pseudo run sort.pseudo --step

ℹ

Special statementsAssignments, swaps, and loops get special step output. All other statements use a default step view.

Combine with --analyze

After stepping through, add --analyze to also see the Big-O complexity:

bash

pseudo run sort.pseudo --step --analyze