6 Pretty-Printing

This library provides facilities for pretty-printing Datalog source. It can be required via:

(require (planet jaymccarthy/datalog:1:0/pretty))

This library depends on the pprint PLaneT package, which can be required via:

  (require (planet dherman/pprint:4))

See the documentation for pprint for information on how to use it.

(format-datum d) → doc?

d : datum/c

Formats a datum.

Examples:

> (pretty-print (format-datum 'sym))

sym

> (pretty-print (format-datum "str"))

"str"

(format-variable v) → doc?

v : variable?

Formats a variable.

Examples:

> (pretty-print (format-variable (make-variable #f 'Ancestor)))

Ancestor

(format-constant c) → doc?

c : constant?

Formats a constant.

Examples:

> (pretty-print (format-constant (make-constant #f 'joseph)))

joseph

> (pretty-print (format-constant (make-constant #f "whom")))

"whom"

(format-term t) → doc?

t : term/c

Formats a term.

Examples:

> (pretty-print (format-term (make-variable #f 'Ancestor)))

Ancestor

> (pretty-print (format-term (make-constant #f 'joseph)))

joseph

> (pretty-print (format-term (make-constant #f "whom")))

"whom"

(format-literal l) → doc?

l : literal?

Formats a literal.

Examples:

> (pretty-print (format-literal (make-literal #f 'true (list))))

true

> (pretty-print      (format-literal       (make-literal #f 'ancestor        (list (make-variable #f 'A) (make-constant #f 'jay)))))

ancestor(A, jay)

> (pretty-print      (format-literal       (make-literal #f '=        (list (make-constant #f 'joseph) (make-constant #f 'jay)))))

joseph = jay

(format-literals ls) → doc?

ls : (listof literal?)

Formats a list of literals as assertions for formatting prove results.

Examples:

> (pretty-print      (format-literals       (list        (make-literal #f 'true (list))        (make-literal #f 'ancestor         (list (make-constant #f 'joseph) (make-constant #f 'jay)))        (make-literal #f '=         (list (make-constant #f 'joseph) (make-constant #f 'jay))))))

true.   ancestor(joseph, jay).   joseph = jay.

(format-clause c) → doc?

c : clause?

Formats a clause.

Examples:

> (pretty-print      (format-clause       (make-clause        #f (make-literal #f 'ancestor            (list (make-constant #f 'joseph)                  (make-constant #f 'jay)))        (list))))

ancestor(joseph, jay)

> (pretty-print      (format-clause       (make-clause        #f (make-literal            #f 'ancestor            (list (make-constant #f 'A) (make-constant #f 'B)))        (list (make-literal               #f 'parent               (list (make-constant #f 'A) (make-constant #f 'B)))))))

ancestor(A, B) :- parent(A, B)

> (pretty-print      (format-clause       (make-clause        #f (make-literal            #f 'ancestor            (list (make-constant #f 'A) (make-constant #f 'B)))        (list (make-literal               #f 'parent               (list (make-constant #f 'A) (make-constant #f 'C)))              (make-literal               #f 'ancestor               (list (make-constant #f 'C) (make-constant #f 'B)))))))

ancestor(A, B) :- parent(A, C), ancestor(C, B)

(format-assertion a) → doc?

a : assertion?

Formats a assertion.

Examples:

> (pretty-print      (format-assertion       (make-assertion        #f (make-clause         #f (make-literal #f 'ancestor             (list (make-constant #f 'joseph)                   (make-constant #f 'jay)))         (list)))))

ancestor(joseph, jay).

(format-retraction r) → doc?

r : retraction?

Formats a retraction.

Examples:

> (pretty-print      (format-retraction       (make-retraction        #f (make-clause         #f (make-literal #f 'ancestor             (list (make-constant #f 'joseph)                   (make-constant #f 'jay)))         (list)))))

ancestor(joseph, jay)~

(format-query q) → doc?

q : query?

Formats a query.

Examples:

> (pretty-print      (format-query       (make-query        #f (make-literal #f 'ancestor            (list (make-constant #f 'joseph)                  (make-constant #f 'jay))))))

ancestor(joseph, jay)?

(format-statement s) → doc?

s : statement/c

Formats a statement.

Examples:

> (pretty-print      (format-statement       (make-query        #f (make-literal #f 'ancestor            (list (make-constant #f 'joseph)                  (make-constant #f 'jay))))))

ancestor(joseph, jay)?

(format-program p) → doc?

p : program/c

Formats a program.

Examples:

> (pretty-print      (format-program       (list        (make-assertion         #f (make-clause          #f (make-literal #f 'ancestor              (list (make-constant #f 'joseph)                    (make-constant #f 'jay)))          (list)))        (make-query         #f (make-literal #f 'ancestor             (list (make-constant #f 'joseph)                   (make-constant #f 'jay)))))))

ancestor(joseph, jay).   ancestor(joseph, jay)?