39 lines
1.2 KiB
Markdown
39 lines
1.2 KiB
Markdown
List is the most fundamental data type. Is a sequencial argument, is a final sequence of element. It is no possible to have more than one element per box.
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There is two different way to declare a list, the recursive one and the iterative one.
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## Recursive list
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- The first box is the **head of the list**
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- The rest of the list is **the tail of the list**
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- The signature of the recursive list is the following:
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```
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TYPES
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list, box
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USES
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element
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OPERATIONS
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emptylist : -> list (* Internal operations of list*)
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cons : list x element -> list (* Internal operations of list *)
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tail : list -> list (* Internal operations of list *)
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head : list -> box (* Internal operations of box *)
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contents : box -> element (* Observer of box *)
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first : list -> element (* Observer of list *)
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next : box -> box (* Internal operation of box *)
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PRECONDITIONS
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tail(_l_) is-defined-iaoi _l_ ≠ emptylist
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head(_l_) is-defined-iaoi _l_ ≠ emptylist
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first(_l_) is-defined-iaoi _l_ ≠ emptylist
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AXIOMS
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first(_l_) = contents(head(_l_))
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tail(cons(_e,l_)) = _l_
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first(cons(_e,l_)) = _e_
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next(head(_l_)) = head(tail(_l_))
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WITH
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list _l_
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element _e_
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```
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