3 Static Types

3.3 Type and Signature Declarations

decl	::=	let_decl
	|	tp_decl
	|	type_ext_decl
	|	object_decl
	|	obj_ext_decl
	|	predicate_decl
	|	disjoint_decl
	|	cover_decl
	|	divide_decl	
	|	signature_decl
	|	method_decl
	|	field_sig_decl
	|	field_decl
	|	precedence_decl
	|	include_decl
	|	prim_decl

The following example illustrates some of the extensions:

object list;
	method is_empty(l@:list):bool { l.length = 0 }
	signature length(l:list):int;
	signature do(l:list, closure:&(int):void):void;
	signature pair_do(l1:list, l2:list, closure:&(int,int):void):void;
	method prepend(x:int, l@:list):list {
		object inherits cons { head := x, tail := l } }
	method copy_reverse(l:list):list {
		let var l2:list := nil;
		do(l, &(x:int){ l2 := prepend(x, l2); };
		l2 }
representation cons isa list;
	field head(@:cons):int;
	field tail(@:cons):list;

3.3.1 - Type Declarations

3.3.2 - Representation and Object Declarations

3.3.3 - Type and Object Extension Declarations

3.3.4 - Signature Declarations

3.3.5 - Implementation and Method Declarations

3.3.6 - Field Implementation Declarations

3.3.7 - Other Type Declarations

3.3.8 - Discussion

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