[bg] starter functions

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ben 2016-03-21 23:48:57 -04:00
parent ea3ed2a762
commit 41968efaea
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bg
===
mlish tests by Ben
- `ps1` :
```
(define (fn-list [f* : (List (→ A A))] [a : A] → A)
(define (count-letters/one [s : String] [c : Char] → Int)
(define (count-letters [s* : (List String)] [c : Char] → Int)
(define (map [f : (→ A B)] [x* : (List A)] → (List B))
(define (append [x* : (List A)] [y* : (List A)] → (List A))
(define (flatten [x** : (List (List A))] → (List A))
(define (insert [x : A] → (→ (List A) (List (List A))))
(define (permutations [x* : (List A)] → (List (List A)))
(define (split [ab* : (List (** A B))] → (** (List A) (List B)))
(define (combine [a*b* : (** (List A) (List B))] → (List (** A B)))
(define (fst [xy : (** A B)] → A)
(define (snd [xy : (** A B)] → B)
(define (foldl [f : (→ A B A)] [acc : A] [x* : (List B)] → A)
(define (sum [x* : (List Float)] → Float)
(define (reverse [x* : (List A)] → (List A))
(define (convolve [x* : (List Float)] [y* : (List Float)] → Float)
(define (mc [n : Int] [f : (→ A A)] [x : A] → A)
(define (square [n : Int] → Int)
(define (successor [mcn : (→ (→ A A) A A)] → (→ (→ A A) A A))
```
-

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#lang s-exp "../../../mlish.rkt"
(require "../../rackunit-typechecking.rkt")
;; =============================================================================
(define-type (List X)
Nil
(Cons X (List X)))
;; =============================================================================
;; http://www.cs.cornell.edu/courses/cs3110/2011fa/hw/ps1/ps1.html
(define (fn-list [f* : (List (→ A A))] [a : A] → A)
(match f* with
[Nil -> a]
[Cons f f* -> (fn-list f* (f a))]))
(check-type
(fn-list (Cons (λ ([x : Int]) (+ x 1)) (Cons (λ ([x : Int]) (* x 2)) Nil)) 4)
: Int
⇒ 10)
;; -----------------------------------------------------------------------------
(define (count-letters/one [s : String] [c : Char] → Int)
(for/sum ([i (in-range (string-length s))])
(if (equal? (string-ref s i) c)
1
0)))
(define (count-letters [s* : (List String)] [c : Char] → Int)
(match s* with
[Nil -> 0]
[Cons s s* -> (+ (count-letters/one s c)
(count-letters s* c))]))
(check-type
(count-letters (Cons "OCaml" (Cons "Is" (Cons "Alot" (Cons "Better" (Cons "Than" (Cons "Java" Nil)))))) (string-ref "a" 0))
: Int
⇒ 4)
;; -----------------------------------------------------------------------------
(define (map [f : (→ A B)] [x* : (List A)] → (List B))
(match x* with
[Nil -> Nil]
[Cons x x* -> (Cons (f x) (map f x*))]))
(define (append [x* : (List A)] [y* : (List A)] → (List A))
(match x* with
[Nil -> y*]
[Cons x x* -> (Cons x (append x* y*))]))
(define (flatten [x** : (List (List A))] → (List A))
(match x** with
[Nil -> Nil]
[Cons x* x** -> (append x* (flatten x**))]))
(define (insert [x : A] → (→ (List A) (List (List A))))
(λ ([x* : (List A)])
(Cons (Cons x x*)
(match x* with
[Nil -> Nil]
[Cons y y* -> (map (λ ([z* : (List A)]) (Cons y z*))
((insert x) y*))]))))
(define (permutations [x* : (List A)] → (List (List A)))
(match x* with
[Nil -> (Cons Nil Nil)]
[Cons x x* -> (flatten (map (insert x) (permutations x*)))]))
(check-type
(permutations (Nil {Int}))
: (List (List Int))
⇒ (Cons (Nil {(List Int)}) Nil))
(check-type
(permutations (Cons 1 Nil))
: (List (List Int))
⇒ (Cons (Cons 1 Nil) Nil))
(check-type
(permutations (Cons 1 (Cons 2 Nil)))
: (List (List Int))
⇒ (Cons (Cons 1 (Cons 2 Nil)) (Cons (Cons 2 (Cons 1 Nil)) Nil)))
(check-type
(permutations (Cons 1 (Cons 2 (Cons 3 Nil))))
: (List (List Int))
⇒ (Cons (Cons 1 (Cons 2 (Cons 3 Nil)))
(Cons (Cons 2 (Cons 1 (Cons 3 Nil)))
(Cons (Cons 2 (Cons 3 (Cons 1 Nil)))
(Cons (Cons 1 (Cons 3 (Cons 2 Nil)))
(Cons (Cons 3 (Cons 1 (Cons 2 Nil)))
(Cons (Cons 3 (Cons 2 (Cons 1 Nil)))
Nil)))))))
;; =============================================================================
;; http://www.cs.cornell.edu/courses/cs3110/2011sp/hw/ps1/ps1.htm
(define-type (** X Y)
(Pair X Y))
(define (split [ab* : (List (** A B))] → (** (List A) (List B)))
(match ab* with
[Nil -> (Pair Nil Nil)]
[Cons ab ab* ->
(match ab with
[Pair a b ->
(match (split ab*) with
[Pair a* b* ->
(Pair (Cons a a*)
(Cons b b*))])])]))
(check-type
(split (Nil {(** Int Int)}))
: (** (List Int) (List Int))
⇒ (Pair (Nil {Int}) (Nil {Int})))
(check-type
(split (Cons (Pair 1 2) (Cons (Pair 3 4) Nil)))
: (** (List Int) (List Int))
⇒ (Pair (Cons 1 (Cons 3 Nil))
(Cons 2 (Cons 4 Nil))))
(check-type
(split (Cons (Pair 1 "one") (Cons (Pair 2 "two") (Cons (Pair 3 "three") Nil))))
: (** (List Int) (List String))
⇒ (Pair (Cons 1 (Cons 2 (Cons 3 Nil)))
(Cons "one" (Cons "two" (Cons "three" Nil)))))
;; -----------------------------------------------------------------------------
(define (combine [a*b* : (** (List A) (List B))] → (List (** A B)))
(match a*b* with
[Pair a* b* ->
(match a* with
[Nil ->
(match b* with
[Nil ->
Nil]
[Cons b b* ->
Nil])] ;; Error
[Cons a a* ->
(match b* with
[Nil ->
Nil] ;; Error
[Cons b b* ->
(Cons (Pair a b) (combine (Pair a* b*)))])])]))
(check-type
(combine (Pair (Nil {Int}) (Nil {Int})))
: (List (** Int Int))
⇒ (Nil {(** Int Int)}))
(check-type
(combine (Pair (Cons 1 (Cons 2 Nil)) (Cons 3 (Cons 4 Nil))))
: (List (** Int Int))
⇒ (Cons (Pair 1 3) (Cons (Pair 2 4) Nil)))
(check-type
(combine (split (Cons (Pair 1 "one") (Cons (Pair 2 "two") (Cons (Pair 3 "three") Nil)))))
: (List (** Int String))
⇒ (Cons (Pair 1 "one") (Cons (Pair 2 "two") (Cons (Pair 3 "three") Nil))))
;; -----------------------------------------------------------------------------
(define (fst [xy : (** A B)] → A)
(match xy with
[Pair x y -> x]))
(define (snd [xy : (** A B)] → B)
(match xy with
[Pair x y -> y]))
(define (foldl [f : (→ A B A)] [acc : A] [x* : (List B)] → A)
(match x* with
[Nil -> acc]
[Cons x x* -> (foldl f (f acc x) x*)]))
(define (sum [x* : (List Float)] → Float)
(foldl fl+ (exact->inexact 0) x*))
(define (reverse [x* : (List A)] → (List A))
(foldl (λ ([x* : (List A)] [x : A]) (Cons x x*)) Nil x*))
(define (convolve [x* : (List Float)] [y* : (List Float)] → Float)
(sum
(map (λ ([xy : (** Float Float)]) (fl* (fst xy) (snd xy)))
(combine (Pair x* (reverse y*))))))
(check-type
(convolve (Cons 1.0 (Cons 2.0 (Cons 3.0 Nil))) (Cons 1.0 (Cons 2.0 (Cons 3.0 Nil))))
: Float
⇒ (fl+ (fl+ (fl* 1.0 3.0) (fl* 2.0 2.0)) (fl* 3.0 1.0)))
;; -----------------------------------------------------------------------------
(define (mc [n : Int] [f : (→ A A)] [x : A] → A)
(for/fold ([x x])
([_i (in-range n)])
(f x)))
(check-type
(mc 3000 (λ ([n : Int]) (+ n 1)) 3110)
: Int
⇒ 6110)
(define (square [n : Int] → Int)
(* n n))
(check-type
(mc 0 square 2)
: Int
⇒ 2)
(check-type
(mc 2 square 2)
: Int
⇒ 16)
(check-type
(mc 3 square 2)
: Int
⇒ 256)
;; -----------------------------------------------------------------------------
(define (successor [mcn : (→ (→ A A) A A)] → (→ (→ A A) A A))
(λ ([f : (→ A A)] [x : A])
(f (mcn f x))))
(check-type
((successor (λ ([f : (→ Int Int)] [x : Int]) (mc 0 f x))) square 2)
: Int
⇒ 4)
(check-type
((successor (successor (λ ([f : (→ Int Int)] [x : Int]) (mc 0 f x)))) square 2)
: Int
⇒ 16)
(check-type
((successor (successor (successor (λ ([f : (→ Int Int)] [x : Int]) (mc 0 f x))))) square 2)
: Int
⇒ 256)
;; # (mc 3 successor) (mc 0) square 2;;