528 lines
12 KiB
Racket
528 lines
12 KiB
Racket
#lang racket/base
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(require racket/contract
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racket/list
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racket/match
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racket/function
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"lang-struct.rkt"
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"match-a-pattern.rkt"
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"enumerator.rkt")
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(provide
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(contract-out
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[lang-enumerators (-> (listof nt?) (hash/c symbol? enum?))]
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[pat-enumerator (-> (hash/c symbol? enum?)
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any/c ;; pattern
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enum?)]
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[enum-ith (-> enum? exact-nonnegative-integer? any/c)]
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[enum? (-> any/c boolean?)]))
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(define (lang-enumerators nts)
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(let* ([l-enums (make-hash)]
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[rec-nt-terms (find-recs nts)]
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[sorted-nts (sort-nt-terms nts rec-nt-terms)])
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(foldl
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(λ (nt m)
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(hash-set
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m
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(nt-name nt)
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(with-handlers
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([exn:fail? fail/enum])
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(rec-pat/enum `(nt ,(nt-name nt))
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sorted-nts
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rec-nt-terms))))
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(hash)
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sorted-nts)))
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(define enum-ith decode)
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(struct decomposition (ctx term))
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(define (pat-enumerator lang-enums pat)
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(enum-names pat
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(sep-names pat)
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lang-enums))
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(define (rec-pat/enum pat nts rec-nt-terms)
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(enum-names pat
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nts
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(sep-names pat)
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rec-nt-terms))
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;; find-recs : lang -> (hash symbol -o> (assoclist rhs bool))
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;; Identifies which non-terminals are recursive
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(define (find-recs nt-pats)
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(define is-rec?
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(case-lambda
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[(n) (is-rec? n (hash))]
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[(nt seen)
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(or (seen? seen (nt-name nt))
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(ormap
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(λ (rhs)
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(let rec ([pat (rhs-pattern rhs)])
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(match-a-pattern
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pat
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[`any #f]
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[`number #f]
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[`string #f]
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[`natural #f]
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[`integer #f]
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[`real #f]
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[`boolean #f]
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[`variable #f]
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[`(variable-except ,s ...) #f]
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[`(variable-prefix ,s) #f]
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[`variable-not-otherwise-mentioned #f]
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[`hole #f]
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[`(nt ,id)
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(is-rec? (make-nt
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id
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(lookup nt-pats id))
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(add-seen seen
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(nt-name nt)))]
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[`(name ,name ,pat)
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(rec pat)]
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[`(mismatch-name ,name ,pat)
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(rec pat)]
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[`(in-hole ,p1 ,p2)
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(or (rec p1)
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(rec p2))]
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[`(hide-hole ,p) (rec p)]
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[`(side-condition ,p ,g ,e) ;; error
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(error 'unsupported "side-condition")]
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[`(cross ,s)
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(error 'unsupported "cross")] ;; error
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[`(list ,sub-pats ...)
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(ormap (λ (sub-pat)
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(match sub-pat
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[`(repeat ,pat ,name ,mismatch)
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(rec pat)]
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[else (rec sub-pat)]))
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sub-pats)]
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[(? (compose not pair?)) #f])))
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(nt-rhs nt)))]))
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(define (calls-rec? rhs recs)
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(let rec ([pat (rhs-pattern rhs)])
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(match-a-pattern
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pat
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[`any #f]
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[`number #f]
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[`string #f]
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[`natural #f]
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[`integer #f]
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[`real #f]
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[`boolean #f]
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[`variable #f]
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[`(variable-except ,s ...) #f]
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[`(variable-prefix ,s) #f]
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[`variable-not-otherwise-mentioned #f]
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[`hole #f]
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[`(nt ,id)
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(hash-ref recs id)]
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[`(name ,name ,pat)
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(rec pat)]
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[`(mismatch-name ,name ,pat)
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(rec pat)]
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[`(in-hole ,p1 ,p2)
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(or (rec p1)
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(rec p2))]
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[`(hide-hole ,p) (rec p)]
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[`(side-condition ,p ,g ,e) ;; error
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(error 'no-enum "side-condition")]
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[`(cross ,s)
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(error 'no-enum "cross")] ;; error
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[`(list ,sub-pats ...)
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(ormap (λ (sub-pat)
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(match sub-pat
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[`(repeat ,pat ,name ,mismatch)
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(rec pat)]
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[else (rec sub-pat)]))
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sub-pats)]
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[(? (compose not pair?)) #f])))
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(define (seen? m s)
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(hash-ref m s #f))
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(define (add-seen m s)
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(hash-set m s #t))
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(let ([recs
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(foldl
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(λ (nt m)
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(hash-set m (nt-name nt) (is-rec? nt)))
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(hash) nt-pats)])
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(foldl
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(λ (nt m)
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(let ([rhs (nt-rhs nt)])
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(hash-set m (nt-name nt)
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(map (λ (rhs)
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(cons rhs (calls-rec? rhs recs)))
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rhs))))
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(hash)
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nt-pats)))
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;; sort-nt-terms : lang (hash symbol -o> (assoclist rhs bool)) -> lang
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(define (sort-nt-terms nt-pats recs)
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(map
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(λ (nt)
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(let ([rec-nts (hash-ref recs (nt-name nt))])
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(make-nt (nt-name nt)
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(sort (nt-rhs nt)
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(λ (r1 r2)
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(and (not (cdr (assoc r1 rec-nts)))
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(cdr (assoc r2 rec-nts))))))))
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nt-pats))
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;; sep-names : single-pattern lang -> (assoclist symbol pattern)
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(define (sep-names pat)
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(let loop ([pat pat]
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[named-pats '()])
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(match-a-pattern
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pat
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[`any named-pats]
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[`number named-pats]
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[`string named-pats]
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[`natural named-pats]
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[`integer named-pats]
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[`real named-pats]
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[`boolean named-pats]
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[`variable named-pats]
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[`(variable-except ,s ...) named-pats]
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[`(variable-prefix ,s) named-pats]
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[`variable-not-otherwise-mentioned named-pats]
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[`hole named-pats]
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;; names inside nts are separate
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[`(nt ,id) named-pats]
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[`(name ,name ,pat)
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(loop pat
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(add-if-new name pat named-pats))]
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[`(mismatch-name ,name ,pat)
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(loop pat
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(add-if-new name pat named-pats))]
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[`(in-hole ,p1 ,p2)
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(loop p2
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(loop p1 named-pats))]
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[`(hide-hole ,p) (loop p named-pats)]
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[`(side-condition ,p ,g ,e) ;; error
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(error 'no-enum "side condition")]
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[`(cross ,s)
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(error 'no-enum "cross")] ;; error
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[`(list ,sub-pats ...)
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(foldl (λ (sub-pat named-pats)
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(match sub-pat
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;; unnamed repeat
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[`(repeat ,pat #f #f)
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(loop pat named-pats)]
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;; named repeat
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[`(repeat ,pat ,name #f)
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(loop pat
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(add-if-new name 'name-r named-pats))]
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;; mismatch named repeat
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[`(repeat ,pat #f ,mismatch)
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(loop pat
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(add-if-new mismatch 'mismatch-r named-pats))]
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;; normal subpattern
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[else (loop sub-pat named-pats)]))
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named-pats
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sub-pats)]
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[(? (compose not pair?))
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named-pats])))
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(define (add-if-new k v l)
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(cond [(assoc k l) l]
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[else (cons `(,k ,v) l)]))
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(define enum-names
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(case-lambda
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[(pat named-pats nts)
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(enum-names-with
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(λ (pat named)
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(pat/enum-with-names pat nts named))
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pat named-pats)]
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[(pat nts named-pats rec-nt-terms)
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(enum-names-with
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(λ (pat named)
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(pat/enum-with-names pat nts named rec-nt-terms))
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pat named-pats)]))
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(define (enum-names-with f pat named-pats)
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(let rec ([named-pats named-pats]
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[env (hash)])
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(cond [(null? named-pats) (f pat env)]
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[else
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(match
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(car named-pats)
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;; named repeat
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[`(,name name-r)
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(error 'unimplemented "named-repeat")]
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;; mismatch repeat
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[`(,name mismatch-r)
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(error 'unimplemented "mismatch-repeat")]
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[`(,name ,pat mismatch)
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(error 'unimplemented "mismatch")]
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;; named
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[`(,name ,pat)
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(map/enum ;; loses bijection
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cdr
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(λ (x) (cons name x))
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(dep/enum
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(f pat env)
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(λ (term)
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(rec (cdr named-pats)
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(hash-set env
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name
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term)))))]
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[else (error 'bad-assoc)])])))
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(define pat/enum-with-names
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(case-lambda
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[(pat nt-enums named-terms)
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(let loop ([pat pat])
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(match-a-pattern
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pat
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[`any
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(sum/enum
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any/enum
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(listof/enum any/enum))]
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[`number num/enum]
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[`string string/enum]
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[`natural natural/enum]
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[`integer integer/enum]
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[`real real/enum]
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[`boolean bool/enum]
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[`variable var/enum]
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[`(variable-except ,s ...)
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;; todo
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(error 'unimplemented "var-except")]
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[`(variable-prefix ,s)
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;; todo
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(error 'unimplemented "var-prefix")]
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[`variable-not-otherwise-mentioned
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(error 'unimplemented "var-not-mentioned")] ;; error
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[`hole
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(const/enum 'hole)]
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[`(nt ,id)
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(hash-ref nt-enums id)]
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[`(name ,name ,pat)
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(const/enum (hash-ref named-terms name))]
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[`(mismatch-name ,name ,pat)
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(error 'unimplemented "mismatch-name")]
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[`(in-hole ,p1 ,p2) ;; untested
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(map/enum
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(λ (t1-t2) ;; loses bijection
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(plug-hole (car t1-t2)
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(cdr t1-t2)))
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(λ (plugged)
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(cons 'hole plugged))
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(prod/enum
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(loop p1)
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(loop p2)))]
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[`(hide-hole ,p)
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(loop p)]
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[`(side-condition ,p ,g ,e)
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(error 'no-enum "side condition")]
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[`(cross ,s)
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(error 'no-enum "cross")]
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[`(list ,sub-pats ...)
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;; enum-list
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(map/enum
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flatten-1
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identity
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(list/enum
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(map
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(λ (sub-pat)
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(match sub-pat
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[`(repeat ,pat #f #f)
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(map/enum
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cdr
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(λ (ts)
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(cons (length ts)
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ts))
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(dep/enum
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nats
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(λ (n)
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(list/enum
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(build-list n (const (loop pat)))))))]
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[`(repeat ,pat ,name #f)
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(error 'unimplemented "named-repeat")]
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[`(repeat ,pat #f ,mismatch)
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(error 'unimplemented "mismatch-repeat")]
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[else (loop sub-pat)]))
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sub-pats)))]
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[(? (compose not pair?))
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(const/enum pat)]))]
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[(pat nts named-terms rec-nt-terms)
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(let loop ([pat pat])
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(match-a-pattern
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pat
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[`any
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(sum/enum
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any/enum
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(listof/enum any/enum))]
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[`number num/enum]
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[`string string/enum]
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[`natural natural/enum]
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[`integer integer/enum]
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[`real real/enum]
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[`boolean bool/enum]
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[`variable var/enum]
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[`(variable-except ,s ...)
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;; todo
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(error 'unimplemented "var except")]
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[`(variable-prefix ,s)
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;; todo
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(error 'unimplemented "var prefix")]
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[`variable-not-otherwise-mentioned
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(error 'unimplemented "var not otherwise mentioned")]
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[`hole
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(const/enum 'hole)]
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[`(nt ,id)
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(let ([rhss (lookup nts id)])
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(apply sum/enum
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(map
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(λ (rhs)
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(cond [(cdr (assoc rhs (hash-ref rec-nt-terms id)))
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(thunk/enum
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+inf.f
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(λ ()
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(rec-pat/enum (rhs-pattern rhs)
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nts
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rec-nt-terms)))]
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[else
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(rec-pat/enum (rhs-pattern rhs)
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nts
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rec-nt-terms)]))
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rhss)))]
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[`(name ,name ,pat)
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(const/enum (hash-ref named-terms name))]
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[`(mismatch-name ,name ,pat)
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(error 'unimplemented "mismatch-name")]
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[`(in-hole ,p1 ,p2) ;; untested
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(map/enum
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(λ (t1-t2)
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(decomposition (car t1-t2)
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(cdr t1-t2)))
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(λ (decomp)
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(cons (decomposition-ctx decomp)
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(decomposition-term decomp)))
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(prod/enum
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(loop p1)
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(loop p2)))]
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[`(hide-hole ,p)
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;; todo
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(loop p)]
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[`(side-condition ,p ,g ,e)
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(error 'no-enum "side-condition")]
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[`(cross ,s)
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(error 'no-enum "cross")]
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[`(list ,sub-pats ...)
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;; enum-list
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(map/enum
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flatten-1
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identity
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(list/enum
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(map
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(λ (sub-pat)
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(match sub-pat
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[`(repeat ,pat #f #f)
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(map/enum
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cdr
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(λ (ts)
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(cons (length ts)
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ts))
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(dep/enum
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nats
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(λ (n)
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(list/enum
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(build-list n (const (loop pat)))))))]
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[`(repeat ,pat ,name #f)
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(error 'unimplemented "named-repeat")]
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[`(repeat ,pat #f ,mismatch)
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(error 'unimplemented "mismatch-repeat")]
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[else (loop sub-pat)]))
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sub-pats)))]
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[(? (compose not pair?))
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(const/enum pat)]))]))
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(define (flatten-1 xs)
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(append-map
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(λ (x)
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(if (or (pair? x)
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(null? x))
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x
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(list x)))
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xs))
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;; lookup : lang symbol -> (listof rhs)
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(define (lookup nts name)
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(let rec ([nts nts])
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(cond [(null? nts) (error 'unkown-nt)]
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[(eq? name (nt-name (car nts)))
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(nt-rhs (car nts))]
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[else (rec (cdr nts))])))
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(define natural/enum nats)
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(define char/enum
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(map/enum
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integer->char
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char->integer
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(range/enum #x61 #x7a)))
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(define string/enum
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(map/enum
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list->string
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string->list
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(listof/enum char/enum)))
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(define integer/enum
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(sum/enum nats
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(map/enum (λ (n) (- (+ n 1)))
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(λ (n) (- (- n) 1))
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nats)))
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(define real/enum (from-list/enum '(0.0 1.5 123.112354)))
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(define num/enum
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(sum/enum natural/enum
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integer/enum
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real/enum))
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(define bool/enum
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(from-list/enum '(#t #f)))
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(define var/enum
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(map/enum
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(compose string->symbol list->string list)
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(compose car string->list symbol->string)
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char/enum))
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(define any/enum
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(sum/enum num/enum
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string/enum
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bool/enum
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var/enum))
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(define (plug-hole ctx term)
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(let loop ([ctx ctx])
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(match
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ctx
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['hole term]
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[`(,ts ...)
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(map loop ts)]
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[x x])))
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(module+ test
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(require rackunit)
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(define rep `(,(make-nt 'r
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`(,(make-rhs `(list variable
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(repeat variable #f #f)))))))
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(define rs (hash-ref (lang-enumerators rep) 'r))
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(test-begin
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(check-equal? (enum-ith rs 0) '(a))
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(check-equal? (size rs) +inf.f))
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(define λc `(,(make-nt 'e
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`(,(make-rhs `(list (repeat variable #f #f)))
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,(make-rhs `(list λ variable (nt e)))
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,(make-rhs `(list (nt e) (nt e)))))))
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(define les (lang-enumerators λc))
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(define es (hash-ref les 'e))
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(check-equal? (size es) +inf.f))
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