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Command Line Interface (CLI)

The Prism CLI provides a complete environment for developing and running Prism programs.

Installation​

# Install globally with npm
npm install -g @prism-lang/cli

# Or with yarn
yarn global add @prism-lang/cli

# Or with pnpm
pnpm add -g @prism-lang/cli

Commands​

prism run <file>​

Execute a Prism program from a file.

# Run a Prism file
prism run script.prism

# Example output
🚀 Running script.prism...

Result: Hello from Prism! (~0.85)

Features:

  • Executes .prism files
  • Shows confidence values in output
  • Supports all Prism language features
  • Configures LLM providers from environment

prism eval <code>​

Evaluate Prism expressions directly from the command line.

# Simple expression
prism eval "2 + 2"
# Output: 4

# With confidence
prism eval "42 ~> 0.9"
# Output: 42 (~0.9)

# Multi-word expressions
prism eval "x = 10; x * 2"
# Output: 20

# LLM calls
prism eval 'llm("Hello AI!")'
# Output: Hello! How can I help you today? (~0.85)

prism or prism repl​

Launch the interactive REPL (Read-Eval-Print Loop).

prism
# Welcome to Prism REPL v1.0.23
# Type expressions and see results with confidence tracking
# Commands: :help, :vars, :clear, :exit
# 
# prism>

REPL Features:

  • Interactive expression evaluation
  • Variable persistence across commands
  • Command history
  • Special commands (:help, :vars, etc.)
  • Multi-line input support

prism --version or prism -v​

Display the installed version.

prism --version
# Prism v1.0.23

prism --help or prism -h​

Show help information and available commands.

Configuration​

LLM Provider Setup​

The CLI automatically configures LLM providers from environment variables:

# Claude (Anthropic)
export CLAUDE_API_KEY=your-api-key

# Google Gemini
export GEMINI_API_KEY=your-api-key

# Default provider (optional)
export PRISM_DEFAULT_LLM=claude  # or 'gemini'

Environment Files​

The CLI loads .env files automatically if present:

# .env file in your project
CLAUDE_API_KEY=sk-ant-...
GEMINI_API_KEY=AIza...
PRISM_DEFAULT_LLM=claude

Examples​

Basic Script​

// analyze.prism
data = "User feedback: The product is amazing but shipping was slow"

sentiment = llm("Analyze sentiment: ${data}") ~> 0.9
entities = llm("Extract entities: ${data}") ~> 0.85

console.log("Sentiment:", sentiment)
console.log("Entities:", entities)

uncertain if (sentiment) {
  high { 
    console.log("✅ Positive feedback detected")
  }
  medium { 
    console.log("⚠️ Mixed feedback detected")
  }
  low { 
    console.log("❌ Negative feedback detected")
  }
}

Run with: prism run analyze.prism

Interactive Development​

$ prism
Welcome to Prism REPL v1.0.23

prism> x = 10 ~> 0.95
10 (~0.95) (confident)

prism> y = 20 ~> 0.90
20 (~0.9) (confident)

prism> x + y
30 (~0.9) (confident)

prism> :vars
Session Variables:
  x: 10 (~95.0%)
  y: 20 (~90.0%)

prism> analysis = llm("What is ${x} + ${y}?")
The sum of 10 + 20 equals 30. (confident)

prism> :exit
Goodbye! 👋

Pipeline Processing​

# Process data through multiple transformations
prism eval 'data = "raw text" |> clean |> analyze |> summarize'

# With confidence tracking
prism eval 'result = input ~> 0.8 |> process ~> 0.9 |> validate ~> 0.95'

Error Handling​

The CLI provides clear error messages:

# Syntax errors
prism eval "x = "
❌ Error: Expected expression after '='

# Runtime errors
prism run nonexistent.prism
❌ Error: File not found: nonexistent.prism

# LLM configuration
prism eval 'llm("test")'
⚠️  Only mock LLM provider available. Set CLAUDE_API_KEY or GEMINI_API_KEY for real AI integration.

Tips​

  1. Use the REPL for experimentation - Test expressions interactively before adding to scripts
  2. Check confidence values - The CLI always shows confidence in output
  3. Set up LLM providers - Export API keys for real AI capabilities
  4. Use .env files - Keep API keys secure and out of scripts
  5. Leverage multi-line input - The CLI handles complex expressions naturally

Troubleshooting​

LLM Provider Not Working​

# Check available providers
prism eval ":llm"

# Verify environment variables
echo $CLAUDE_API_KEY
echo $GEMINI_API_KEY

Command Not Found​

# Verify installation
npm list -g @prism-lang/cli

# Reinstall if needed
npm install -g @prism-lang/cli

File Encoding Issues​

Ensure .prism files are saved with UTF-8 encoding for proper string handling.