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REPL (Interactive Shell)

Harneet includes an interactive Read–Eval–Print Loop (REPL) for quickly testing code, exploring APIs, and iterating on ideas.

Start the REPL

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./harneet --repl
# or via just
just repl

You should see the prompt:

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harneet →

Multiline Editing

The REPL supports multiline input: - Balanced delimiters keep the continued prompt until closed: (), [], {}. - Quoted strings keep the continued prompt until closed. - A trailing backslash \ continues to the next line. - Entering a blank line submits the current block.

Continued prompt: 

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        …

Example:

REPL Function Example
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function add(a int, b int) int {
    return a + b
}

add(2, 3)

Interactive History

  • Use Up/Down arrow keys to navigate history.
  • Press Ctrl-R to search history (prompts for a term and recalls the latest match).
  • History is persisted to ~/.harneet_history with newlines escaped.

View or search from within the REPL: - :history – Show all history entries - :search <term> – Filter history by substring (case-insensitive)

Editor Integration

Open your editor to write a block and run it on exit:

  • :edit – Opens $EDITOR. Fallbacks: vim, nano, vi, ed.

Variable Inspection

Inspect currently visible variables across scopes:

  • :vars

Example output: 

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answer = 42
name = Alice

File Operations

  • :load <file> – Run the contents of a file in the current REPL environment
  • :save <file> – Save the last submitted block to a file

Environment Management

  • :reset – Reset the REPL environment (clears variables)
  • :quit, :q, exit – Exit the REPL

Command Summary

  • :help – Show help
  • :edit – Open editor and run on exit
  • :history – Show persisted history
  • :search <term> – Filter history
  • :vars – List current variables
  • :load <file> – Run a file into the current environment
  • :save <file> – Save last submitted block
  • :reset – Reset environment
  • :quit | :q | exit – Exit

Tips

  • Multiline blocks are submitted on a blank line.
  • History stores each submitted block as a single entry (with newlines escaped).
  • For complex edits, use :edit to take advantage of your editor features.