stricli

name	stricli
description	Build type-safe CLI applications with Stricli. Use when creating command-line tools with TypeScript, defining commands with flags/positional args, organizing multi-command CLIs with route maps, or needing compile-time parameter validation.

Stricli CLI Framework

Stricli is Bloomberg's type-safe CLI framework for TypeScript. It provides compile-time type checking for command parameters, automatic help generation, and flexible command routing.

Quick Start

Create a minimal single-command CLI:

1. Installation

npm install @stricli/core
# or
bun add @stricli/core

2. Project Structure

my-cli/
├── src/
│   ├── commands/
│   │   └── greet.ts      # Command implementation
│   ├── app.ts            # Application entry point
│   └── index.ts          # CLI runner
├── package.json
└── tsconfig.json

3. Define a Command (src/commands/greet.ts)

import { buildCommand } from "@stricli/core";

export interface GreetFlags {
    readonly name: string;
    readonly shout: boolean;
}

export const greet = buildCommand({
    docs: {
        brief: "Greet a user",
        description: "Prints a greeting message to the console"
    },
    parameters: {
        flags: {
            name: {
                kind: "parsed",
                brief: "Name to greet",
                parse: String,
                default: "World"
            },
            shout: {
                kind: "boolean",
                brief: "Use uppercase",
                default: false
            }
        }
    },
    func(flags: GreetFlags) {
        const message = `Hello, ${flags.name}!`;
        console.log(flags.shout ? message.toUpperCase() : message);
    }
});

4. Build Application (src/app.ts)

import { buildApplication } from "@stricli/core";
import { name, version, description } from "../package.json";
import { greet } from "./commands/greet";

export const app = buildApplication({
    name,
    version,
    description,
    command: greet
});

5. Run CLI (src/index.ts)

import { run } from "@stricli/core";
import { app } from "./app";

await run(app, process.argv.slice(2));

6. Configure package.json

{
  "name": "my-cli",
  "version": "1.0.0",
  "type": "module",
  "bin": {
    "my-cli": "./dist/index.js"
  },
  "scripts": {
    "build": "tsc",
    "start": "node dist/index.js"
  }
}

Core Concepts

buildCommand

Creates a command with typed parameters and an execution function.

buildCommand({
    docs: { brief, description },
    parameters: { flags, positional },
    func(flags, positional, context) {
        // Implementation
    }
});

buildRouteMap

Organizes multiple commands into a routed structure.

buildRouteMap({
    routes: {
        create: createCommand,
        delete: deleteCommand,
        list: listCommand
    },
    docs: {
        brief: "Manage resources"
    }
});

buildApplication

Wraps a command or route map into an executable application.

buildApplication({
    name: "my-cli",
    version: "1.0.0",
    description: "CLI description",
    command: routeMap  // or single command
});

run

Executes the application with provided arguments.

await run(app, process.argv.slice(2), context);

Parameter Types

Flag Parameters

Flags are named parameters using --flag-name or -f syntax.

Boolean Flags

flags: {
    verbose: {
        kind: "boolean",
        brief: "Enable verbose output",
        default: false
    }
}

Usage: --verbose or --no-verbose

Counter Flags

flags: {
    verbose: {
        kind: "counter",
        brief: "Verbosity level"
    }
}

Usage: -v, -vv, -vvv (counts occurrences)

Enum Flags

flags: {
    format: {
        kind: "enum",
        values: ["json", "yaml", "text"],
        brief: "Output format",
        default: "text"
    }
}

Parsed Flags

flags: {
    port: {
        kind: "parsed",
        parse: Number,
        brief: "Port number",
        default: 3000
    }
}

Built-in parsers: String, Number, numberParser, booleanParser

Variadic Flags

flags: {
    include: {
        kind: "variadic",
        parse: String,
        brief: "Files to include"
    }
}

Usage: --include file1.ts --include file2.ts Result: flags.include is string[]

Positional Parameters

Positional parameters are unnamed arguments passed by position.

Tuple Positional (Fixed Count)

positional: {
    kind: "tuple",
    parameters: [
        {
            brief: "Source file",
            parse: String
        },
        {
            brief: "Destination file",
            parse: String
        }
    ]
}

Usage: my-cli source.txt dest.txt

Array Positional (Variable Count)

positional: {
    kind: "array",
    parameter: {
        brief: "Files to process",
        parse: String
    }
}

Usage: my-cli file1.txt file2.txt file3.txt Result: positional is string[]

Workflow

Building a Single-Command CLI

1. Define command - Create command file with buildCommand
2. Implement function - Add business logic in func property
3. Build application - Wrap command with buildApplication
4. Run - Execute with run(app, args)

Building a Multi-Command CLI

1. Define commands - Create multiple command files
2. Create route map - Organize commands with buildRouteMap
3. Build application - Pass route map to buildApplication
4. Run - Execute with command routing: my-cli create ...

Adding Custom Parsers

const urlParser = (input: string): URL => {
    try {
        return new URL(input);
    } catch (error) {
        throw new Error(`Invalid URL: ${input}`);
    }
};

flags: {
    endpoint: {
        kind: "parsed",
        parse: urlParser,
        brief: "API endpoint URL"
    }
}

Using Custom Context

Pass shared state/dependencies to all commands:

interface AppContext {
    readonly config: Config;
    readonly logger: Logger;
}

// In func
func(flags, positional, context: AppContext) {
    context.logger.info("Running command...");
}

// When running
await run(app, args, { config, logger });

Multi-Command Structure

Nested Routes

const projectRoutes = buildRouteMap({
    routes: {
        create: createProjectCommand,
        delete: deleteProjectCommand,
        list: listProjectsCommand
    },
    docs: { brief: "Manage projects" }
});

const taskRoutes = buildRouteMap({
    routes: {
        add: addTaskCommand,
        complete: completeTaskCommand
    },
    docs: { brief: "Manage tasks" }
});

const rootRoutes = buildRouteMap({
    routes: {
        project: projectRoutes,
        task: taskRoutes
    }
});

const app = buildApplication({
    name: "pm",
    version: "1.0.0",
    command: rootRoutes
});

Usage:

• pm project create myapp
• pm project list
• pm task add "Write docs"

Lazy Loading

For large CLIs, use lazy loading to improve startup time:

const routes = buildRouteMap({
    routes: {
        heavy: {
            lazy: async () => {
                const mod = await import("./commands/heavy");
                return mod.heavyCommand;
            },
            brief: "Heavy operation"
        }
    }
});

Built-in Features

Automatic Help

Stricli generates help text from docs.brief and docs.description:

my-cli --help
my-cli command --help

Version Display

my-cli --version

Common Patterns

Input Validation

func(flags) {
    if (flags.port < 1 || flags.port > 65535) {
        throw new Error("Port must be between 1 and 65535");
    }
}

Async Operations

async func(flags) {
    const data = await fetchData(flags.url);
    console.log(data);
}

Error Handling

func(flags) {
    try {
        // Operation
    } catch (error) {
        console.error(`Error: ${error.message}`);
        process.exit(1);
    }
}

Testing Commands

Commands are pure functions - easy to test:

import { test, expect } from "bun:test";
import { greet } from "./commands/greet";

test("greet with default name", () => {
    const output: string[] = [];
    const mockConsole = {
        log: (msg: string) => output.push(msg)
    };

    greet.func.call(
        { console: mockConsole },
        { name: "World", shout: false },
        undefined,
        undefined
    );

    expect(output[0]).toBe("Hello, World!");
});

Reference Documentation

For detailed API documentation and complete examples, see:

• API Reference - Complete API for buildCommand, buildRouteMap, buildApplication, all parameter kinds, and parsers
• Examples - Complete working examples including multi-command CLIs, custom parsers, and advanced patterns

Additional Resources

• Stricli GitHub
• Official Documentation
• NPM Package

When to Use Stricli

Use Stricli when:

• Building TypeScript CLIs with type safety
• Need compile-time parameter validation
• Want automatic help generation
• Building multi-command CLIs with routing
• Need complex parameter parsing

Consider alternatives when:

• Building simple scripts (native process.argv may suffice)
• Working in pure JavaScript (no TypeScript)
• Need different paradigm (e.g., inquirer for prompts)