iantayler / rizzi Goto Github PK

This is an interpreter for (right now, a fragment of) the Rizzi programming language written in Go.

Syntactically, this is how the fragment works. Terminals are between '':

PROGRAM			-> MAIN '[' ID ']' STATEMENTLIST END

STATEMENTLIST   	-> STATEMENT STATEMENTLIST

STATEMENT		-> EXPR | ORDER | ASSIGNMENT

ASSIGNMENT		-> ID '=' EXPR

ORDER			-> 'if' EXPR 'then' STATEMENTLIST 'end' |

				'for' EXPR 'do' STATEMENTLIST 'end'
	   
EXPR			-> mathemathical expressions with +, *, -, integer /,

				rem, neg, succ, pred, exp, numbers and variables.
	   
ID			-> variable names

MAIN			-> 'main' | 'm'

END			-> 'end' | 'e'

Statements should be on separate lines. The parser works fine when that's the case but I'm not entirely sure why (which is pretty bad).

A program returns its last statement. Running the interpreter like "rizzi FILE -a ARG" passes ARG as an argument. That argument is saved in a variable with the name between '[' and ']'.

There's some syntactic bugs which restrict where we can put IDs. Right now they can be circumvented by writing '0 + var' instead of 'var' when a problem arises, but that's going to be fixed eventually. There's also syntactic bugs in the way we deal with parentheses.

#TODO (in order. FIFO):

• Fix syntactic bugs on variables and parentheses.

• Add a 'print' order.

• Add multiple variables to programs.

• Add a type system with:

• Short-term:

  • i. Integers and natural numbers (i.e. unsigned integers) as distinct types.
  • ii. Type inference.
  • iii. Pairs with elements of arbitrary type.

• Mid- and long-term:

  • iv. Lists (perhaps we can use pairs and pointers to pairs internally)
  • v. Bytes
  • vi. Structs

• Perhaps:

  • vi. UTF-8 characters and UTF-8 strings.

• Add function declarations and functions as first-class types.

• Lexical scope.

• The Go API.