2 Quick Language Overview

This is a high-level description of language features to set the stage for starting to discuss the implementation. For a more detailed description (no language lawyer formal specification :-)), see section 10. For quick view of the simple hosting and runtime API, see section 22.

SymPL stands for symbolic programming language. It is pronounced as "simple" and is usually written as "Sympl". It looks like a Lisp variant, but it lacks several of Lisp's semantics. For example, Sympl does NOT:

• evaluate identifiers by indirecting through a symbol's value cell (Sympl is like Common Lisp lexical variables)

• have symbols with distinct value and function value cells (only value cells)

• read all code into a list literal, have a *readtable*, read macros, etc.

• allow all identifiers to be redefined (Sympl has keywords)

Sympl has very minimal language features and simple .NET interoperability for instructional purposes only. Sympl has:

• pure expression-based semantics (easy with Expression Trees v2)

• a simplified module mechanism akin to python's

• hosting model for executing files and snippets within host-provided scopes

• top-level functions and global variables within file modules

• closures (free with the DLR)

• basic data types: int, string, double

• basic control flow: if, loop, function call

• basic arithmetic, Boolean, and comparison operations

• infix dot for accessing data and function members

• case-insensitive identifiers