expression ->
	| sequence
//	| apply
	| unary
	| binary
//	| let
	| compound
	| control
	| field
	| index
	| identifier
	| primary

grouping -> "(" expression ")" ;
unary -> ( "-" | "!" ) expression ;
binary -> expression operator expression ;
operator ->
	| "==" | "!=" | "<" | "<=" | ">" | ">="
	| "+" | "-" | "*" | "/"
//	| "|>" | "<|" | ">>" | "<<"
	| "++" ;
control ->
	| if
	| when
if -> "if" expression "then" expression "else" expression ;
variant_pattern -> "`" identifier ( "(" ( ( "_" | identifier ) ( "," ( "_" | identifier )* )? ) ")" )? ;
when -> "when" expression "is" ( variant_pattern "=>" expression )+ ;
compound -> variant | record | list ;
variant -> "`" identifier ( "(" ( expression ( "," expression)* )? ")" )? ;
base_record -> expression ( "with" identifier "=" expression ( "," "with" identifier "=" expression )* )?
record ->
	"{" ( identifier ("=" expression)? ( "," identifier ("=" expression)? )* )? ( "|" base_record )* "}" ;
list -> "[" ( expression ( "," expression )* )? "]" ;
field -> expression "." identifier ;
index -> expression "[" expression "]" ;
identifier -> IDENTIFIER | "@" STRING ;
primary -> NUMBER | STRING | identifier | "(" expression ")" ;