45 lines
1.5 KiB
Racket
45 lines
1.5 KiB
Racket
#lang typed/racket/base
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(require "lexical-structs.rkt")
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(provide (all-defined-out))
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;; Expressions
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(define-type ExpressionCore (U Top Constant Var Branch Def Lam Seq App #;Letrec))
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(define-struct: Top ([prefix : Prefix]
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[code : ExpressionCore]) #:transparent)
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(define-struct: Constant ([v : Any]) #:transparent)
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(define-struct: Var ([id : Symbol]) #:transparent)
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(define-struct: Branch ([predicate : ExpressionCore]
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[consequent : ExpressionCore]
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[alternative : ExpressionCore]) #:transparent)
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(define-struct: Def ([variable : Symbol]
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[value : ExpressionCore]) #:transparent)
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(define-struct: Lam ([parameters : (Listof Symbol)]
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[body : ExpressionCore]) #:transparent)
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(define-struct: Seq ([actions : (Listof ExpressionCore)]) #:transparent)
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(define-struct: App ([operator : ExpressionCore]
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[operands : (Listof ExpressionCore)]) #:transparent)
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#;(define-struct: Letrec ([names : (Listof Symbol)]
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[procs : (Listof Lam)]
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[body : ExpressionCore]))
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(: last-exp? ((Listof Expression) -> Boolean))
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(define (last-exp? seq)
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(null? (cdr seq)))
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(: first-exp ((Listof Expression) -> Expression))
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(define (first-exp seq) (car seq))
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(: rest-exps ((Listof Expression) -> (Listof Expression)))
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(define (rest-exps seq) (cdr seq))
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(define-struct: Assign ([variable : Symbol]
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[value : Expression]) #:transparent)
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(define-type Expression (U ExpressionCore #;Assign))
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