92 lines
3.1 KiB
Racket
92 lines
3.1 KiB
Racket
#lang typed/racket
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;;; dds/bn
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;;; This module provides some quick definitions for running Boolean
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;;; networks. A Boolean network is a set of Boolean variables which
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;;; are updated according to their corresponding update functions.
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;;; The variables to be updated at each step are given by the mode.
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(require "utils.rkt")
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(provide Variable State UpdateFunc Network
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update make-state make-bn-funcs update-func-form->update-func
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bn-form->bn make-bn-forms
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bn)
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;;; =================
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;;; Basic definitions
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;;; =================
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(define-type Variable Symbol)
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;;; A state of a Boolean network is a mapping from the variables of the
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;;; network to their Boolean values.
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(define-type State (HashTable Variable Boolean))
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;;; An update function is a Boolean function computing a Boolean value
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;;; 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
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;;; functions.
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(define-type Network (HashTable Variable UpdateFunc))
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;;; Given a state s updates all the variables from xs. This
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;;; corresponds to a parallel mode.
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(: update (-> Network State (Listof Variable) State))
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(define (update bn ; the Boolean network
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s ; the state to operate on
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xs) ; the variables to update
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(let ([new-s : State (hash-copy s)])
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(for ([x xs])
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(let ([f (hash-ref bn x)])
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(hash-set! new-s x (f s))))
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new-s))
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;;; A version of make-hash restricted to creating Boolean states.
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(: make-state (-> (Listof (Pairof Variable Boolean)) State))
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(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.
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(: make-bn-funcs (-> (Listof (Pairof Variable UpdateFunc)) Network))
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(define (make-bn-funcs funcs)
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(make-hash funcs))
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;;; =========================================
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;;; Syntactic description of Boolean networks
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;;; =========================================
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;;; An UpdateFuncForm is any form which can appear as a body of a
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;;; Boolean function and which can be evaluated with eval. For
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;;; example, '(and x y (not z)).
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(define-type UpdateFuncForm Any)
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;;; A Boolean network form is a mapping from its variables to the
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;;; forms of their update functions.
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(define-type NetworkForm (HashTable Variable UpdateFuncForm))
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;;; Build an update function from an update function form.
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#;(: update-func-form->update-func (-> UpdateFuncForm UpdateFunc))
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(define (update-func-form->update-func form)
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(lambda ([s : State])
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(cast (eval-with1 (cast s (HashTable Variable Any)) form) Boolean)))
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;;; Build a Network from a Network form.
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(: bn-form->bn (-> NetworkForm Network))
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(define (bn-form->bn bnf)
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(make-hash
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(hash-map bnf (lambda ([x : Variable] [form : UpdateFuncForm])
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(cons x (update-func-form->update-func form))))))
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;;; Build a network from a list of pairs of forms of update functions.
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(: make-bn-forms (-> (Listof (Pairof Variable UpdateFuncForm)) Network))
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(define (make-bn-forms forms)
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(bn-form->bn (make-hash forms)))
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;;; A shortcut for make-bn-forms.
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(define-syntax-rule (bn forms) (make-bn-forms forms))
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