Overview

• Define the new language's concrete syntax
• Define the new language's abstract syntax
• Define the meaning of each syntactic element using a known language
  • Evaluation semantics (execution)
  • Static semantics (type checking)

There are three ways of doing this:

• denotational - map each language structure to a mathematical function
• operational - define how legal strings in a language are evaluated
• axiomatic - define pre/post-conditions on execution of language constructs

Defining Syntax

A set of language rules can be infinitely large with a finite number of symbols

Interpreters

Generally, they map language to a value.

$E:L\to V$

Parser will translate numbers into the language.

Common Symbols (important):
! - bank
? - hook
* - splat
#! - shebang