debug.elpi

type nodebug, debug, debug_fails_only, checks prop.
type indent int -> prop.

announce G :- bracket "." ">>" G "\n", fail.

% a possible use is to check that intermediate terms and tipes are wellformed.
check P :- checks, !, P.
check _.

indent 0.
spy G :- not nodebug, debug, !, indent X, Y is X + 1, ((indent Y :- !) => spy' G).
spy G :- G, !.
spy G :- debug_fails_only, bracket "+" "]Fail  \n" G "\n",  fail.

spy' G :-  (bracket "_" "[Begin\n" G "\n", G, !, bracket "-" "]Success\n" G "\n"). 
spy' G :-  bracket "+" "]Fail  \n" G "\n",  fail.

bracket IndentChar Open G Close 
	:- indent N
	, indent_str N IndentChar IndentStr
	, term_to_string G S
	, term_to_string N Ns
	, Output is (Ns ^ IndentStr ^ Open ^ S ^ Close)
	, print Output.

%indent_str 0 _ "" :- !.
indent_str N _ "" :- (N - 1) < 0 , !.
indent_str N C S1 :- N' is (N - 1), indent_str N' C S2, S1 is S2 ^ C. 


makeline :- print "||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||".