df741faa83
Right now, the syntax sugar provided by Cur is instructive, but annoying to use. Time to make it easier to use.
30 lines
598 B
Racket
30 lines
598 B
Racket
#lang s-exp "../cur.rkt"
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(require
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"nat.rkt"
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"maybe.rkt"
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"sugar.rkt")
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(provide
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List
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nil
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cons
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list-ref)
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(data List : (-> (A : Type) Type)
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(nil : (-> (A : Type) (List A)))
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(cons : (-> (A : Type) A (List A) (List A))))
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(define list-ref
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(elim
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List
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Type
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(lambda (A : Type) (ls : (List A))
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(-> Nat (Maybe A)))
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(lambda (A : Type) (n : Nat) (none A))
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(lambda (A : Type) (a : A) (ls : (List A)) (ih : (-> Nat (Maybe A)))
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(lambda (n : Nat)
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(match n
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[z (some A a)]
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[(s (n-1 : Nat))
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(ih n-1)])))))
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