====== Picotalk ======

Picotalk is a simple Smalltalk-like programming language and environment implemented in ECMAScript (JavaScript), mainly intended (but not limited) to teaching basic concepts of programming.

Project page at berliOS: [[https://developer.berlios.de/projects/picotalk/]]

===== Picotalk Isn't Smalltalk =====

Picotalk

  * **Case is important**: Picotalk distinguishes between identifiers starting with an uppercase letter and those starting with a lowercase letter. A beginning uppercase letter denotes a global name, e.g. a class name. 
  * **Brace array literals**: Picotalk only supports the brace array notation for array literals. 
  * **Declaration of temporaries is a statement**:



===== Data Structures =====

All data structures (AST, runtime objects) are now pure JSON data structures. This allows easier transport ove

==== AST Nodes ====

Each AST node is represented by a plain JavaScript object. The type of an AST node is determined by its ''type'' property. Legal values are the 

^ Type ^ Properties ^
| (all) | ''loc'' |
| **Code** ||
| Script | ''args'', ''stmts'' |
| Block | ''args'', ''stmts'' |
| Method | ''kind'', ''selector'', ''args'', ''stmts'' |
| **Misc Statements** ||
| Temporaries | ''temps'' |
| Return | ''expr '' | 
| **Expressions** ||
| Assignment | ''name'', ''expr '' |
| MessageSend | ''kind'', ''selector'', ''receiver'', ''args'' |
| Name | ''name'' |
| GlobalName | ''name'' |
| Literal | ''literal'' |
| Self | - |
| Super | - |
| BraceArray | ''exprs'' |
| Primitive | ''module'', ''method'' |

===== Bytecode =====

Picotalk code is compiled to bytecode. In the current version the generated "bytecode" is just a simple JavaScript array.

^ Opcode ^ Parameters ^ Description ^
| NOP | - | Does nothing |
| PUSH_NIL | - | Pushes the ''nil'' object onto the stack |

===== History ======

  * Nov 2006: All AST node objects are now pure JSON data structures.