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32 lines
798 B
Racket
32 lines
798 B
Racket
#lang racket/base
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(require "define/contract.rkt")
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(module+ test (require rackunit))
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(define+provide/contract (filter-tree proc tree)
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(procedure? list? . -> . list?)
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(define (remove-empty x)
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(cond
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[(list? x) (filter (compose1 not null?) (map remove-empty x))]
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[else x]))
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(define (filter-tree-inner proc x)
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(cond
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[(list? x) (map (λ(i) (filter-tree-inner proc i)) x)]
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[else (if (proc x) x null)]))
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(remove-empty (filter-tree-inner proc tree)))
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(define+provide/contract (filter-not-tree proc tree)
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(procedure? list? . -> . list?)
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(filter-tree (λ(i) (not (proc i))) tree))
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(define+provide/contract (map-tree proc tree)
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(procedure? list? . -> . list?)
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(cond
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[(list? tree) (map (λ(i) (map-tree proc i)) tree)]
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[else (proc tree)]))
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