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Create archiver and offline code handlers

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Somewhat messy. Will clean up gradually in future commits.
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Cadence Ember 2023-02-05 17:56:15 +13:00
parent b8e5fb8dc5
commit c7cce5479d
Signed by untrusted user: cadence
GPG key ID: BC1C2C61CF521B17
46 changed files with 4274 additions and 407 deletions
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lib/syntax.rkt Normal file
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#lang racket/base
(require (for-syntax racket/base))
(provide
; help make a nested if. if/in will gain the same false form of its containing if/out.
if/out
; let, but the value for each variable is evaluated within a thread
thread-let
; cond, but values can be defined between conditions
cond/var
; wrap sql statements into lambdas so they can be executed during migration
wrap-sql)
(module+ test
(require rackunit)
(define (check-syntax-equal? s1 s2)
(check-equal? (syntax->datum s1)
(syntax->datum s2))))
;; actual transforming goes on in here.
;; it's in a submodule so that it can be required in both levels, for testing
(module transform racket/base
(require racket/list)
(provide
transform-if/out
transform-thread-let
transform/out-cond/var)
(define (transform-if/out stx)
(define tree (cdr (syntax->datum stx))) ; condition true false
(define else (cddr tree)) ; the else branch cons cell
(define result
(let walk ([node tree])
(cond
; normally, node should be a full cons cell (a pair) but it might be something else.
; situation: reached the end of a list, empty cons cell
[(null? node) node]
; situation: reached the end of a list, cons cdr was non-list
[(symbol? node) node]
; normal situation, full cons cell
; -- don't go replacing through nested if/out
[(and (pair? node) (eq? 'if/out (car node))) node]
; -- replace if/in
[(and (pair? node) (eq? 'if/in (car node)))
(append '(if) (walk (cdr node)) else)]
; recurse down pair head and tail
[(pair? node) (cons (walk (car node)) (walk (cdr node)))]
; something else that can't be recursed into, so pass it through
[#t node])))
(datum->syntax stx (cons 'if result)))
(define (transform-thread-let stx)
(define tree (cdr (syntax->datum stx)))
(define defs (car tree))
(define forms (cdr tree))
(when (eq? (length forms) 0)
(error (format "thread-let: bad syntax (need some forms to execute after the threads)~n forms: ~a" forms)))
(define counter (build-list (length defs) values))
(datum->syntax
stx
`(let ([chv (build-vector ,(length defs) (λ (_) (make-channel)))])
,@(map (λ (n)
(define def (list-ref defs n))
`(thread (λ () (channel-put (vector-ref chv ,n) (let _ () ,@(cdr def))))))
counter)
(let ,(map (λ (n)
(define def (list-ref defs n))
`(,(car def) (channel-get (vector-ref chv ,n))))
counter)
,@forms))))
(define (transform/out-cond/var stx)
(define tree (transform-cond/var (cdr (syntax->datum stx))))
(datum->syntax
stx
tree))
(define (transform-cond/var tree)
(define-values (els temp) (splitf-at tree (λ (el) (and (pair? el) (not (eq? (car el) 'var))))))
(define-values (vars rest) (splitf-at temp (λ (el) (and (pair? el) (eq? (car el) 'var)))))
(if (null? rest)
`(cond ,@els)
`(cond
,@els
[#t
(let ,(for/list ([var vars])
(cdr var))
,(transform-cond/var rest))]))))
;; the syntax definitions and their tests go below here
(require 'transform (for-syntax 'transform))
(define-syntax (wrap-sql stx)
; the arguments
(define xs (cdr (syntax->list stx)))
; wrap each argument
(define wrapped (map (λ (xe) ; xe is the syntax of an argument
(if (list? (car (syntax->datum xe)))
; it's a list of lists (a list of sql migration steps)
; return instead syntax of a lambda that will call everything in xe
(datum->syntax stx `(λ () ,@xe))
; it's just a single sql migration step
; return instead syntax of a lambda that will call xe
(datum->syntax stx `(λ () ,xe))))
xs))
; since I'm returning *code*, I need to return the form (list ...) so that runtime makes a list
(datum->syntax stx `(list ,@wrapped)))
(define-syntax (if/out stx)
(transform-if/out stx))
(module+ test
(check-syntax-equal? (transform-if/out #'(if/out (condition 1) (if/in (condition 2) (do-yes)) (do-no)))
#'(if (condition 1) (if (condition 2) (do-yes) (do-no)) (do-no)))
(check-equal? (if/out #t (if/in #t 'yes) 'no) 'yes)
(check-equal? (if/out #f (if/in #t 'yes) 'no) 'no)
(check-equal? (if/out #t (if/in #f 'yes) 'no) 'no)
(check-equal? (if/out #f (if/in #f 'yes) 'no) 'no))
(define-syntax (thread-let stx)
(transform-thread-let stx))
(module+ test
; check that it is transformed as expected
(check-syntax-equal?
(transform-thread-let
#'(thread-let ([a (hey "this is a")]
[b (hey "this is b")])
(list a b)))
#'(let ([chv (build-vector 2 (λ (_) (make-channel)))])
(thread (λ () (channel-put (vector-ref chv 0) (let _ () (hey "this is a")))))
(thread (λ () (channel-put (vector-ref chv 1) (let _ () (hey "this is b")))))
(let ([a (channel-get (vector-ref chv 0))]
[b (channel-get (vector-ref chv 1))])
(list a b))))
; check that they actually execute concurrently
(define ch (make-channel))
(check-equal? (thread-let ([a (begin
(channel-put ch 'a)
(channel-get ch))]
[b (begin0
(channel-get ch)
(channel-put ch 'b))])
(list a b))
'(b a))
; check that it assigns the correct value to the correct variable
(check-equal? (thread-let ([a (sleep 0) 'a] [b 'b]) (list a b))
'(a b)))
(define-syntax (cond/var stx)
(transform/out-cond/var stx))
(module+ test
(check-syntax-equal? (transform/out-cond/var #'(cond/def [#f 0] (var d (* a 2)) [(eq? d 8) d] [#t "not 4"]))
#'(cond
[#f 0]
[#t
(let ([d (* a 2)])
(cond
[(eq? d 8) d]
[#t "not 4"]))])))