1 | include "Maybe.ma". |
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2 | include "Nat.ma". |
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3 | |
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4 | ninductive List (A: Type[0]): Type[0] ≝ |
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5 | Empty: List A |
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6 | | Cons: A → List A → List A. |
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7 | |
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8 | notation "hvbox(hd break :: tl)" |
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9 | right associative with precedence 47 |
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10 | for @{ 'Cons $hd $tl }. |
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11 | |
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12 | interpretation "Empty" 'Empty = (Empty ?). |
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13 | interpretation "Cons" 'Cons = (Cons ?). |
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14 | |
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15 | notation "[ list0 x sep ; ]" |
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16 | non associative with precedence 90 |
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17 | for @{ fold right @'Empty rec acc @{ 'Cons $x $acc } }. |
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18 | |
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19 | nlet rec length (A: Type[0]) (l: List A) on l ≝ |
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20 | match l with |
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21 | [ Empty ⇒ Z |
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22 | | Cons hd tl ⇒ S (length A tl) |
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23 | ]. |
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24 | |
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25 | nlet rec append (A: Type[0]) (l: List A) (m: List A) on l ≝ |
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26 | match l with |
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27 | [ Empty ⇒ m |
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28 | | Cons hd tl ⇒ hd :: (append A tl l) |
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29 | ]. |
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30 | |
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31 | notation "hvbox(l break @ r)" |
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32 | right associative with precedence 47 |
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33 | for @{ 'append $l $r }. |
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34 | |
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35 | interpretation "Append" 'append = (append ?). |
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36 | |
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37 | nlet rec fold_right (A: Type[0]) (B: Type[0]) |
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38 | (f: A → B → B) (x: B) (l: List A) on l ≝ |
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39 | match l with |
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40 | [ Empty ⇒ x |
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41 | | Cons hd tl ⇒ f hd (fold_right A B f x tl) |
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42 | ]. |
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43 | |
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44 | nlet rec fold_left (A: Type[0]) (B: Type[0]) |
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45 | (f: A → B → A) (x: A) (l: List B) on l ≝ |
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46 | match l with |
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47 | [ Empty ⇒ x |
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48 | | Cons hd tl ⇒ f (fold_left A B f x tl) hd |
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49 | ]. |
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50 | |
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51 | nlet rec map (A: Type[0]) (B: Type[0]) |
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52 | (f: A → B) (l: List A) on l ≝ |
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53 | match l with |
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54 | [ Empty ⇒ Empty B |
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55 | | Cons hd tl ⇒ f hd :: map A B f tl |
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56 | ]. |
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57 | |
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58 | nlet rec null (A: Type[0]) (l: List A) on l ≝ |
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59 | match l with |
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60 | [ Empty ⇒ True |
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61 | | Cons hd tl ⇒ False |
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62 | ]. |
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63 | |
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64 | nlet rec reverse (A: Type[0]) (l: List A) on l ≝ |
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65 | match l with |
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66 | [ Empty ⇒ Empty A |
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67 | | Cons hd tl ⇒ reverse A tl @ (Cons A hd (Empty A)) |
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68 | ]. |
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69 | |
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70 | ndefinition head ≝ |
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71 | λA: Type[0]. |
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72 | λl: List A. |
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73 | match l with |
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74 | [ Empty ⇒ Nothing A |
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75 | | Cons hd tl ⇒ Just A hd |
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76 | ]. |
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77 | |
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78 | ndefinition tail ≝ |
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79 | λA: Type[0]. |
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80 | λl: List A. |
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81 | match l with |
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82 | [ Empty ⇒ Nothing (List A) |
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83 | | Cons hd tl ⇒ Just (List A) tl |
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84 | ]. |
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85 | |
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86 | nlet rec replicate (A: Type[0]) (n: Nat) (a: A) on n ≝ |
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87 | match n with |
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88 | [ Z ⇒ Empty A |
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89 | | S o ⇒ a :: (replicate A o a) |
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90 | ]. |
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