145 lines
5.6 KiB
Racket
145 lines
5.6 KiB
Racket
#lang scribble/lp2
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@(require "../lib/doc.rkt")
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@doc-lib-setup
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@title[#:style manual-doc-style]{Algebaraic Data Types:
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@racket[define-constructor] and @racket[define-tagged]}
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@(table-of-contents)
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@section{Introduction}
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@section{@racket[uninterned] and @racket[private]}
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We wish to be able to declare tags and constructors only
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visible to the creator, unlike the default ones which can be
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instantiated and matched against anonymously.
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We will define two flavours. In the first case,
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@tc[uninterned] constructors inherit the interned one. It
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means that the interned constructor is a supertype of the
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uninterned constructor (but not the converse). Two distinct
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uninterned constructors with the same name are unrelated
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too. The second possibility is to declare a @tc[private]
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constructor, where the private constructor inherits directly
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from @tc[ConstructorTop], the base structure described in
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section @secref{constructor|supertype}, and is therefore
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unrelated to the interned constructor (and is unrelated to
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the uninterned constructor too).
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The choice to declare an uninterned or private
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@CHUNK[<uninterned+private>
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(define/syntax-parse ((~maybe with-struct declare-uninterned/private))
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(cond [(attribute uninterned)
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#`(#,(syntax-local-introduce #'constructor-name)
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declare-uninterned-constructor-struct)]
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[(attribute private)
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#`(#,(syntax-local-introduce #'constructor-name)
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declare-constructor-struct)]
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[else #'()]))]
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The above code binds @tc[declare-uninterned/private] to
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either @tc[declare-uninterned-constructor-struct] or
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@tc[declare-constructor-struct], depending on the keyword
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used. The macro's expansion will use this to declare
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@tc[with-struct].
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@chunk[<declare-uninterned-or-private-struct>
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(?? (declare-uninterned/private with-struct))]
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@section{@racket{define-constructor}}
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@chunk[<define-constructor>
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(define-syntax/parse
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(define-constructor constructor-name:id
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(~maybe (~optkw #:uninterned) (~optkw #:private))
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(~maybe #:? name?)
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type …)
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(define/with-syntax default-name? (format-id #'name "~a?" #'name))
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(define-temp-ids "pat" (type …))
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(define-temp-ids "value" (type …))
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<uninterned+private>
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(template
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(begin
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<declare-uninterned-or-private-struct>
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(define-multi-id constructor-name
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#:type-expand-once
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(constructor constructor-name
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(?? (?@ #:with-struct with-struct))
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type …)
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#:match-expander
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(λ/syntax-parse (_ pat …)
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#'(constructor constructor-name
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(?? (?@ #:with-struct with-struct))
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pat …))
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#:call
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(λ/syntax-parse (_ value …)
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#'(constructor constructor-name
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(?? (?@ #:with-struct with-struct))
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value …)))
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(define-multi-id (?? name? default-name?)
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#:else
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#'(constructor? constructor-name
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(?? (?@ #:with-struct with-struct)))))))]
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@chunk[<define-tagged>
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(define-syntax/parse (define-tagged constructor-name:id
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(~maybe (~optkw #:uninterned) (~optkw #:private))
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(~maybe #:? name?)
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[field type] …)
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(define/with-syntax default-name? (format-id #'name "~a?" #'name))
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(define-temp-ids "pat" (type …))
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(define-temp-ids "value" (type …))
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<uninterned+private>
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(template
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(begin
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<declare-uninterned-or-private-struct>
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(define-multi-id constructor-name
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#:type-expand-once
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(tagged constructor-name
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(?? (?@ #:with-struct with-struct))
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[field type] …)
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#:match-expander
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(λ/syntax-parse (_ pat …)
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#'(tagged constructor-name
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(?? (?@ #:with-struct with-struct))
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[field pat] …))
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#:call
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(λ/syntax-parse (_ value …)
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#'(tagged #:instance
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constructor-name
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(?? (?@ #:with-struct with-struct))
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[field value] …)))
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(define-multi-id (?? name? default-name?)
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#:else
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#'(tagged? constructor-name
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(?? (?@ #:with-struct with-struct))
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field …)))))]
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@section{Conclusion}
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@chunk[<*>
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(begin
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(module main typed/racket
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(require (for-syntax racket/list
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syntax/parse
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syntax/parse/experimental/template
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racket/syntax
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(submod phc-toolkit untyped))
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(for-meta 2 racket/base)
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"constructor.lp2.rkt"
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(submod "constructor.lp2.rkt" main private)
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"tagged.lp2.rkt"
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phc-toolkit
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"../type-expander/multi-id.lp2.rkt"
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"../type-expander/type-expander.lp2.rkt")
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(provide define-constructor
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define-tagged)
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<define-constructor>
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<define-tagged>)
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(require 'main)
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(provide (all-from-out 'main)))] |