100hellos/picolisp repository overview

⁠Hello World! From picolisp.

Language page⁠ — context, influences, and learning notes on the 100hellos site.

Source on GitHub⁠ (100hellos/picolisp)

⁠Trying it

docker run --rm --platform="linux/amd64" 100hellos/picolisp:latest

⁠Modifying it

Read the repo README⁠, or fork the project⁠ and customize it.

For an interactive shell:

docker run --rm --platform="linux/amd64" --entrypoint="" -it 100hellos/picolisp:latest zsh

⁠PicoLisp

PicoLisp is a minimalist yet powerful Lisp dialect that combines simplicity with remarkable functionality. Created by Alexander Burger, it embodies the philosophy that "less is more" - providing a complete programming environment in an extremely compact implementation.

⁠What Makes PicoLisp Special

PicoLisp is unique among Lisp dialects for several reasons:

⁠Minimalist Design

• The entire system fits in less than 300KB
• Only seven data types: Numbers, Symbols, Lists, and four internal types
• No built-in compiler - it's a pure interpreter optimized for interactive development
• Cells are only 16 bytes (8 bytes on 32-bit systems)

⁠Integrated Database

Unlike most languages, PicoLisp includes a built-in object-oriented database with:

• ACID transactions
• B-Tree indexes
• Entity-relationship modeling
• Seamless persistence without external dependencies

⁠Web Framework

PicoLisp comes with a complete web application framework featuring:

• HTTP server
• HTML generation functions
• Session management
• Form handling and validation

⁠Prolog Engine

A complete Prolog implementation is built into the language, allowing logic programming alongside functional programming paradigms.

⁠Language Philosophy

PicoLisp follows several key principles:

• Simplicity: Every feature must justify its existence
• Orthogonality: Features should not overlap or interfere
• Consistency: Similar things should work similarly
• Efficiency: Both in terms of memory and execution speed

The language intentionally lacks many "convenience" features found in other Lisps, such as:

• Macros (replaced by read macros and let expressions)
• Multiple namespaces (everything is in one global space)
• Complex numeric types (only 64-bit integers and unlimited precision big integers)

⁠Understanding the Hello World Code

#!/usr/bin/env pil

(prinl "Hello World!")
(bye)

Let's break this down:

• #!/usr/bin/env pil - The shebang line tells the system to use the PicoLisp interpreter
• (prinl "Hello World!") - The prinl function prints its arguments followed by a newline
• (bye) - Exits the PicoLisp interpreter gracefully

In PicoLisp, prinl is preferred over print for simple text output because it automatically adds a newline, making output more readable in interactive sessions.

⁠Language History

PicoLisp was created by Alexander Burger, who started development in the 1980s as a reaction to the increasing complexity of other Lisp systems. The first public version was released in 1999.

Key milestones:

• 1980s: Initial development begins
• 1999: First public release
• 2002: Database integration completed
• 2007: 64-bit version released
• 2010: Web framework stabilized
• 2017: Moved to a more open development model

The name "PicoLisp" reflects its tiny size (pico = 10^-12) compared to other Lisp implementations, while still being a complete development environment.

⁠Interactive Development

PicoLisp excels at interactive development. You can explore the language interactively:

# Start the REPL
pil

# Try some basic expressions
: (+ 1 2 3)
-> 6

# Work with lists
: (list 'a 'b 'c)
-> (a b c)

# Define and use functions
: (de hello (name) (prinl "Hello " name "!"))
-> hello

: (hello "World")
Hello World!
-> "World"

⁠Further Exploration

To dive deeper into PicoLisp:

1. Interactive Tutorial: Start with pil and explore the built-in help system
2. Documentation: Visit the official PicoLisp website for comprehensive documentation
3. Examples: The distribution includes many example programs
4. Community: Join the PicoLisp mailing list for discussions and support

PicoLisp proves that a language doesn't need to be large to be powerful. Its integrated approach to programming, databases, and web development makes it a unique tool for building complete applications with minimal overhead.