Add table->function.
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2 changed files with 25 additions and 25 deletions
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@ -19,7 +19,7 @@
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pseudovariadic-lambda pvλ pseudovariadic-define pvdefine
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tabulate* tabulate*/strict tabulate*/pv tabulate tabulate/strict tabulate/pv
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tabulate*/pv/boolean tabulate/pv/boolean tabulate*/pv/01 tabulate/pv/01
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table->function/list)
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table->function/list table->function)
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(module+ test
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(require typed/rackunit))
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@ -206,6 +206,17 @@
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(check-true (negation/list '(#f)))
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(check-false (negation/list '(#t)))))
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(: table->function (All (a) (-> (Listof (Listof a)) (-> a * a))))
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(define (table->function table)
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(define func (table->function/list table))
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(λ args (func args)))
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(module+ test
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(test-case "table->function"
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(define negation (table->function '((#t #f) (#f #t))))
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(check-true (negation #f))
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(check-false (negation #t))))
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(module untyped racket
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(module+ test
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(require rackunit))
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@ -287,7 +298,7 @@
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tabulate tabulate/strict tabulate/pv
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tabulate*/pv/boolean tabulate/pv/boolean
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tabulate*/pv/01 tabulate/pv/01
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table->function/list)
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table->function/list table->function)
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(require (rename-in (submod 'typed untyped)
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[tabulate tabulate/untyped]
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@ -299,7 +310,6 @@
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[struct tbf ((weights (vectorof number?)) (threshold number?))])
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;; Functions
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(contract-out
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[table->function (-> (listof (*list/c any/c any/c)) procedure?)]
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[enumerate-boolean-tables (-> number? (stream/c (listof (*list/c boolean? boolean?))))]
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[enumerate-boolean-functions (-> number? (stream/c procedure?))]
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[enumerate-boolean-functions/list (-> number? (stream/c procedure?))]
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@ -332,28 +342,6 @@
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;;; Constructing functions
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;;; ======================
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;;; Given a table like the one produced by the tabulate functions,
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;;; creates a function which has this behaviour.
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;;;
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;;; More exactly, the input is a list of lists of values. All but the
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;;; last elements of every list give the values of the parameters of
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;;; the function, while the the last element of every list gives the
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;;; value of the function. Thus, every list should have at least two
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;;; elements.
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;;;
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;;; The produced function is implemented via lookups in hash tables,
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;;; meaning that it may be sometimes more expensive to compute than by
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;;; using an direct symbolic implementation.
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(define (table->function table)
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(let ([func (table->function/list table)])
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(λ args (func args))))
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(module+ test
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(test-case "table->function"
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(define negation (table->function '((#t #f) (#f #t))))
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(check-true (negation #f))
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(check-false (negation #t))))
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;;; Returns the stream of the truth tables of all Boolean functions of
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;;; a given arity.
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;;;
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@ -261,6 +261,18 @@ last element.
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(and/list '(#t #t))
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]}
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@defproc[(table->function [table (Listof (Listof a))])
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(-> a * a)]{
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Like @racket[table->function/list], but the resulting function takes a variable
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number of arguments rather than a list of values.
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@examples[#:eval functions-evaluator
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(define my-and (table->function tab))
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(my-and #f #t)
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(my-and #t #t)
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]}
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@section{Random functions}
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@section{Threshold Boolean functions}
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