dds/bn.rkt

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#lang typed/racket
;;; dds/bn
;;; This module provides some quick definitions for running Boolean
;;; networks. A Boolean network is a set of Boolean variables which
;;; are updated according to their corresponding update functions.
;;; The variables to be updated at each step are given by the mode.
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(provide Variable State UpdateFunc Network
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update make-state make-bn)
(define-type Variable Symbol)
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;;; A state of a Boolean network is a mapping from the variables of the
;;; network to their Boolean values.
(define-type State (HashTable Variable Boolean))
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;;; An update function is a Boolean function computing a Boolean value
;;; from the given state.
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(define-type UpdateFunc (-> State Boolean))
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;;; A Boolean network is a mapping from its variables to its update
;;; functions.
(define-type Network (HashTable Variable UpdateFunc))
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;;; Given a state s updates all the variables from xs. This
;;; corresponds to a parallel mode.
(: update (-> Network State (Listof Variable) State))
(define (update bn ; the Boolean network
s ; the state to operate on
xs) ; the variables to update
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(let ([new-s : State (hash-copy s)])
(for ([x xs])
(let ([f (hash-ref bn x)])
(hash-set! new-s x (f s))))
new-s))
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;;; A version of make-hash restricted to creating Boolean states.
(: make-state (-> (Listof (Pairof Variable Boolean)) State))
(define (make-state mappings)
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(make-hash mappings))
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;;; A version of make-hash restricted to creating Boolean networks.
(: make-bn (-> (Listof (Pairof Variable UpdateFunc)) Network))
(define (make-bn funcs)
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(make-hash funcs))