#+TITLE: Guise

* Overview

Guise is a concatenative, functional, statically-typed, stack-based language with S-expression syntax, implemented in Guile.

It combines:
- *Joy's* pure concatenative semantics
- *Factor's* practical stack language design
- *Scheme's* S-expression syntax
- *ML's* algebraic data types and static type inference
  
* Key Features

** Stack-Based Evaluation
All computation happens through stack manipulation. Operations execute left-to-right, consuming and producing values on the stack.

** First-Class Quotations
Code blocks are first-class values that can be passed around and executed with =call=.

** Algebraic Data Types
Define product types (tuples) and sum types (tagged unions) with auto-generated constructors and accessors.

** Static Type Inference
Type signatures are checked at compile time, with full type inference for stack effects.

** Module System
Organize code with modules, imports, and public/private visibility control.


* Quick Start

** Running the REPL

#+BEGIN_SRC bash
GUILE_LOAD_PATH=src GUILE_AUTO_COMPILE=0 guile --language=guise
#+END_SRC

*Note:* =GUILE_AUTO_COMPILE=0= prevents Guile from trying to compile Scheme runtime modules using the Guise compiler.

** Running Examples

#+BEGIN_SRC bash
GUILE_LOAD_PATH=src GUILE_AUTO_COMPILE=0 guile --language=guise < examples/basic.guise
#+END_SRC

** Your First Guise Program

#+BEGIN_SRC scheme
;; Stack operations - left to right evaluation
(5 3 +)           ; Push 5, push 3, add → 8
(dup *)           ; Duplicate top, multiply → square

;; Define a word (function) with stack effect signature
(define square (number -> number)
  (dup *))

(5 square)        ; → 25

;; Quotations are first-class code blocks
'(dup *)          ; Push quotation onto stack
(5 '(dup *) call) ; Execute quotation → 25

;; Higher-order functions
(define twice ('a (quot ('a -> 'a)) -> 'a)
  (dup call call))

(5 'square twice) ; → 625 (5 squared twice)
#+END_SRC

* Examples

See the =examples/= directory:
- =basic.guise= - Basic arithmetic and stack operations
- =quotations.guise= - Higher-order functions with quotations
- =numbers.guise= - Number type hierarchy examples
- =tuples.guise= - Tuple construction and operations

* Documentation

** Language Reference
- [[file:doc/syntax.org][BNF Grammar]] - Formal syntax specification

* Contributing

Guise is in active development. Contributions, feedback, and ideas are welcome!

* License

Guise is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

See the [[file:COPYING][COPYING]] file for the full license text, or visit [[https://www.gnu.org/licenses/gpl-3.0.html][GPL-3.0]].