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implement math, tweak syntax

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This commit is contained in:
Jeremy Penner 2022-03-27 12:26:26 -04:00
parent e1e0e168b6
commit 6d46d0f638
3 changed files with 36 additions and 27 deletions
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4
waltz/macros.fnl
View file

@ -5,7 +5,9 @@
(fn clause [c]
(match c
(where [:hashfn expr] (list? c)) `[:const ,expr]
(where [name & params] (list? c)) `[:literal ,(tostring name) ,(icollect [_ param (ipairs params)] (clause param))]
(where [name & params] (sequence? c)) `[:literal ,(tostring name) ,(icollect [_ param (ipairs params)] (clause param))]
(where [head & args] (list? c) (sym? head)) (icollect [_ expr (ipairs args) :into [(tostring head)]] (clause expr))
(where c (list? c)) (icollect [_ val (ipairs c)] (clause val))
(where v (sym? c)) `[:var ,(tostring v)]
_ `[:const ,c]))

51
waltz/sqlog.fnl
View file

@ -19,37 +19,39 @@
; case and build up from there.
; simple queries:
; (p x y) -> SELECT p.c1 AS x, p.c2 AS y FROM p
; (p 1 y) -> SELECT p.c2 AS y FROM p WHERE p.c1 = 1
; (q x) (p x 1) -> SELECT q.c1 AS x FROM q JOIN p WHERE p.c1 = q.c1 AND p.c2 = 1
; (p 1 2) -> SELECT true FROM p WHERE p.c1 = 1 AND p.c2 = 2
; (p 1 x) (p x 2) -> SELECT t1.c2 AS x FROM p AS t1 JOIN p AS t2 WHERE t1.c1 = 1 AND t1.c2 = t2.c1 AND t2.c2 = 2
; [p x y] -> SELECT p.c1 AS x, p.c2 AS y FROM p
; [p 1 y] -> SELECT p.c2 AS y FROM p WHERE p.c1 = 1
; [q x] [p x 1] -> SELECT q.c1 AS x FROM q JOIN p WHERE p.c1 = q.c1 AND p.c2 = 1
; [p 1 2] -> SELECT true FROM p WHERE p.c1 = 1 AND p.c2 = 2
; [p 1 x] [p x 2] -> SELECT t1.c2 AS x FROM p AS t1 JOIN p AS t2 WHERE t1.c1 = 1 AND t1.c2 = t2.c1 AND t2.c2 = 2
; queries using rules:
; [(ancestor x y) (parent x y)] -> SELECT p.c1 AS x, p.c2 AS y FROM parent AS p
; [(ancestor x y) (parent x z) (ancestor z y)] -> SELECT p.c1 AS x, a.y AS y FROM parent AS p JOIN ancestor AS a WHERE p.c1 = a.x AND p.c2 = a.y
; (ancestor x :john) -> WITH RECURSIVE ancestor(x, y) AS (SELECT ... UNION SELECT ...) SELECT a.c1 AS x FROM ancestor AS a WHERE a.y = 'john'
; [(ancestor :bob x) (ancestor x :john)] -> SELECT 'bob' AS c1, a.c1 AS c2 FROM ancestor AS a WHERE a.c2 = 'john'
; ([ancestor x y] [parent x y]) -> SELECT p.c1 AS x, p.c2 AS y FROM parent AS p
; ([ancestor x y] [parent x z] [ancestor z y]) -> SELECT p.c1 AS x, a.y AS y FROM parent AS p JOIN ancestor AS a WHERE p.c1 = a.x AND p.c2 = a.y
; [ancestor x :john] -> WITH RECURSIVE ancestor(x, y) AS (SELECT ... UNION SELECT ...) SELECT a.c1 AS x FROM ancestor AS a WHERE a.y = 'john'
; ([ancestor :bob x] [ancestor x :john]) -> SELECT 'bob' AS c1, a.c1 AS c2 FROM ancestor AS a WHERE a.c2 = 'john'
; queries with comparisons? arithmetic operations? function calls?
; (p x y) (< x 5) -> SELECT p.c1 AS x, p.c2 AS y FROM p WHERE p.c1 < 5
; (p x y) (q (+ x 1)) -> SELECT p.c1 AS x, p.c2 AS y FROM p JOIN q WHERE q.c1 = p.c1 + 1
; (p (+ x 1) y) (q x) -> SELECT q.c1 AS x, p.c2 AS y FROM p JOIN q WHERE p.c1 + 1 = q.c1
; (p (+ x 1) x) -> SELECT p.c2 AS x FROM p WHERE p.c1 + 1 = p.c2
; queries with arithmetic operations (function calls?)
; [p x y] [q (+ x 1)] -> SELECT p.c1 AS x, p.c2 AS y FROM p JOIN q WHERE q.c1 = p.c1 + 1
; [p (+ x 1) y] [q x] -> SELECT q.c1 AS x, p.c2 AS y FROM p JOIN q WHERE p.c1 = q.c1 + 1
; [p (+ x 1) x] -> SELECT p.c2 AS x FROM p WHERE p.c1 = p.c2 + 1
; queries with comparisons
; [p x y] (< x 5) -> SELECT p.c1 AS x, p.c2 AS y FROM p WHERE p.c1 < 5
; confusing expressions we probably won't support:
; (p (+ x 1) (* x 2)) -> SELECT p.c1 - 1 AS x FROM p WHERE p.c1 + 1 = p.c2 * 2??
; [p (+ x 1) (* x 2)] -> SELECT p.c1 - 1 AS x FROM p WHERE p.c1 + 1 = p.c2 * 2??
; no, that's not right - this says x+1 = c1 AND x*2 = c2
; (p (+ x 1) (* x 2)) -> SELECT p.c1 - 1 AS x FROM p WHERE p.c2 = (p.c1 - 1) * 2
; (p (+ x 1) y) -> meaningless? or...
; [p (+ x 1) (* x 2)] -> SELECT p.c1 - 1 AS x FROM p WHERE p.c2 = (p.c1 - 1) * 2
; [p (+ x 1) y] -> meaningless? or...
; -> SELECT p.c1 - 1 AS x, p.c2 AS y FROM p
; is there a way to trick sql into generating x = p.c1 - 1 from p.c1 = x + 1?
; (p z y) (= z (+ x 1))
; [p z y] (= z (+ x 1))
; unsupported: inline comparisons, explicit equality checks (use unification instead)
; (p (< x 5) y) -> SELECT p.c1 AS x, p.c2 AS y FROM p WHERE p.c1 < 5 -- does this make sense? seems hard to read, hard to parse
; (p x y) (= x y) -> unnecessary, can be written (p x x)
; (p x y) (= x (+ y 1)) -> unnecessary, can be written (p (+ x 1) x)?
; [p (< x 5) y] -> SELECT p.c1 AS x, p.c2 AS y FROM p WHERE p.c1 < 5 -- does this make sense? seems hard to read, hard to parse
; [p x y] (= x y) -> unnecessary, can be written (p x x)
; [p x y] (= x (+ y 1)) -> unnecessary, can be written (p (+ x 1) x)?
(fn Sqlog.new [self]
(set self.tables {})
@ -96,7 +98,8 @@
(each [icolumn value (ipairs params)]
(match value
[:var varname] (self:reference-variable analysis varname [:column itable icolumn])
[:const val] (add-clause analysis [:= [:column itable icolumn] [:const val]])
[:const val] (add-clause analysis [:= [:column itable icolumn] [:const val]])
[op & args] (add-clause analysis [:= [:column itable icolumn] value])
_ (error (.. "expected var or const, got " (fv value))))))
_ (error (.. "Expected literal but got " (fv literal)))))
@ -109,6 +112,7 @@
:constants (or (?. ?parent :constants) [])
:referenced-rules (or (?. ?parent :referenced-rules) [])})
(local infix-ops (collect [_ op (ipairs [:+ :- :* :/ :< :> :<= :>= := :|| :and :or])] op true))
(fn Sqlog.gen-expr [self analysis expr]
(match expr
[:const val] (do (table.insert analysis.constants val) "?")
@ -117,7 +121,8 @@
colnames (. colnames icolumn)
_ (.. "c" icolumn)))
[:as subexpr name] (.. (self:gen-expr analysis subexpr) " AS " name)
[:= lhs rhs] (.. (self:gen-expr analysis lhs) " = " (self:gen-expr analysis rhs))
(where [:var name] (. analysis.variable-mapping name)) (self:gen-expr analysis (. analysis.variable-mapping name))
(where [op lhs rhs] (. infix-ops op)) (.. (self:gen-expr analysis lhs) " " op " " (self:gen-expr analysis rhs))
_ (error (.. "Unrecognized expression " (fv expr)))))
(fn cat [list sep ?f]

8
waltz/sqltest.fnl
View file

@ -3,8 +3,10 @@
(local s (Sqlog))
(s:deftable :parent :parent :child)
(s:deftable :p :x :y)
(s:deftable :q :z)
(defrules s
[(ancestor x y) (parent x y)]
[(ancestor x y) (parent x z) (ancestor z y)])
(pp (query s (ancestor x y)))
([ancestor x y] [parent x y])
([ancestor x y] [parent x z] [ancestor z y]))
(pp (query s [p x y] [q (+ x 1)]))