In this course we will be creating a small programming language called CatScript
catscript_program= { program_statement };
program_statement=statement|function_declaration;
statement=for_statement|if_statement|print_statement|variable_statement|assignment_statement|function_call_statement;
for_statement='for', '(', IDENTIFIER, 'in', expression')', '{', { statement }, '}';
if_statement='if', '(', expression, ')', '{', { statement }, '}' [ 'else', ( if_statement|'{', { statement }, '}' ) ];
print_statement='print', '(', expression, ')'variable_statement='var', IDENTIFIER, [':', type_expression, ] '=', expression;
function_call_statement=function_call;
assignment_statement=IDENTIFIER, '=', expression;
function_declaration='function', IDENTIFIER, '(', parameter_list, ')'+ [ ':'+type_expression ], '{', { function_body_statement }, '}';
function_body_statement=statement|return_statement;
parameter_list= [ parameter, {','parameter } ];
parameter=IDENTIFIER [ , ':', type_expression ];
return_statement='return' [, expression];
expression=equality_expression;
equality_expression=comparison_expression { ("!="|"==") comparison_expression };
comparison_expression=additive_expression { (">"|">="|"<"|"<=" ) additive_expression };
additive_expression=factor_expression { ("+"|"-" ) factor_expression };
factor_expression=unary_expression { ("/"|"*" ) unary_expression };
unary_expression= ( "not"|"-" ) unary_expression|primary_expression;
primary_expression=IDENTIFIER|STRING|INTEGER|"true"|"false"|"null"|list_literal|function_call|"(", expression, ")"list_literal='[', expression, { ',', expression } ']'; function_call=IDENTIFIER, '(', argument_list , ')'argument_list= [ expression , { ',' , expression } ]
type_expression='int'|'string'|'bool'|'object'|'list' [, '<' , type_expression, '>']
CatScript is statically typed, with a small type system as follows
- int - a 32 bit integer
- string - a java-style string
- bool - a boolean value
- list - a list of value with the type 'x'
- null - the null type
- object - any type of value