I have the following:
:- use_module(library(csv)).
:- dynamic mb/3.
:- dynamic mb_column_keys/1.
prepare_db(File) :-
retractall(mb_column_keys(_)),
retractall(mb(_,_,_)),
forall(read_row(File, Row), store_row(Row)).
store_row(Row) :-
Row =.. [row|Cols],
( mb_column_keys(ColKeys)
-> Cols = [RowKey|Samples],
maplist(store_sample(RowKey), ColKeys, Samples)
; (Cols = [_H|T],assertz(mb_column_keys(T)))
).
store_sample(RowKey, ColKey, Sample) :-
assertz(mb(RowKey, ColKey, Sample)).
read_row(File, Row) :-
csv_read_file_row(File, Row, []),
writeln(read_row(Row)).
What is the best way to adapt this so that prepare_db can take two additional arguments to define the predicates for column_keys and mb.
For example ?-prepare_db('my_file.csv',mb_column_keys,mb).
Would result in facts being asserted for mb/3 and mb_column_keys/1
Ok I have changed the file to the following which works:
:- use_module(library(csv)).
:- set_prolog_stack(global, limit(4*10**9)).
prepare_db(File, Column_Key,Relation) :-
Column_Key_Term =.. [Column_Key,_],
Relation_Term =.. [Relation,_,_,_],
retractall(Column_Key_Term),
retractall(Relation_Term),
forall(read_row(File, Row), store_row(Row,Column_Key,Relation)).
store_row(Row,Column_Key,Relation) :-
Column_Key_Test =.. [Column_Key,ColKeys],
Row =.. [row|Cols],
( call(Column_Key_Test)
-> Cols = [RowKey|Values],
maplist(store_relation(Relation,RowKey), ColKeys, Values)
; ( Cols = [_H|T],
Column_Key_Term =.. [Column_Key,T],
assertz(Column_Key_Term)
)
).
store_relation(Relation,RowKey, ColKey, Values) :-
Relation_Term =.. [Relation,RowKey,ColKey,Values],
assertz(Relation_Term).
read_row(File, Row) :-
csv_read_file_row(File, Row, []),
writeln(read_row(Row)).
But it does seem a bit ugly, is there a more elegant way to accomplish this?
Since retractall/1 declares its argument as a dynamic, you could pass a list of predicate Heads to prepare_db, like this:
prepare_db(File, Heads) :-
maplist(retractall, Heads),
% etc
?- prepare_db('my_file.csv', [mb_column_keys(_) ,mb(_,_,_)]).
And keep in mind that SWI-Prolog at least allows you to call dynamic/1:
?- foo(_).
ERROR: toplevel: Undefined procedure: foo/1 (DWIM could not correct goal)
?- dynamic(foo/1).
true.
?- foo(_).
false.
(You would see this is possible if you read between the lines of the footnote to the documentation of retractall/1...)
As false remarked under your question, there are reasons why it would be still good to declare your dynamic predicates.