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magistraleinformaticanetworking:spm:ocamlfs1
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magistraleinformaticanetworking:spm:ocamlfs1 [23/03/2011 alle 16:07 (13 anni fa)] Marco Danelutto |
magistraleinformaticanetworking:spm:ocamlfs1 [23/03/2011 alle 16:22 (13 anni fa)] Marco Danelutto |
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| Linea 3: | Linea 3: | ||
| This is an summary of the lesson given on March 23rd. | This is an summary of the lesson given on March 23rd. | ||
| - | We represent the functional semantics of skeletons with higher order functions. We use [[http:// | + | We represent the functional semantics of skeletons with higher order functions. We use [[http:// |
| Assuming that //data streams// are represented with Ocaml lists (just for the moment), a **farm** skeleton may be defined as follows: | Assuming that //data streams// are represented with Ocaml lists (just for the moment), a **farm** skeleton may be defined as follows: | ||
| Linea 30: | Linea 30: | ||
| # (farm sq) [1; | # (farm sq) [1; | ||
| - : int list = [1; 4; 9; 16; 25] | - : int list = [1; 4; 9; 16; 25] | ||
| + | # | ||
| + | </ | ||
| + | |||
| + | Suppose we also use lists to represent arrays. The map skeleton can be modelled through the **List.map** function, available as primitive in Ocaml and having the obvious type: | ||
| + | < | ||
| + | # List.map;; | ||
| + | - : ('a -> 'b) -> 'a list -> 'b list = <fun> | ||
| + | # | ||
| + | </ | ||
| + | Therefore we can look at the type of skeleton composition. As an example, a farm having a map worker computing sq on all the elements of the matrix (which is actually a vector represented as a list, in our simple assumption) has type: | ||
| + | < | ||
| + | # farm (List.map sq);; | ||
| + | - : int list list -> int list list = <fun> | ||
| + | # | ||
| + | </ | ||
| + | and in fact, giving the composite skeleton a stream (a list, in our assumption) of arrays (vectors represented as a stream, in our assumptions), | ||
| + | < | ||
| + | # let array1 = [1;2];; | ||
| + | val array1 : int list = [1; 2] | ||
| + | # let array2 = [3;4];; | ||
| + | val array2 : int list = [3; 4] | ||
| + | # let stream = [array1; | ||
| + | val stream : int list list = [[1; 2]; [3; 4]] | ||
| + | # farm (List.map sq) stream;; | ||
| + | - : int list list = [[1; 4]; [9; 16]] | ||
| + | # | ||
| + | </ | ||
| + | |||
| + | This is a little bit ambiguous due to the usage of lists to represent both streams and arrays. | ||
| + | Ocaml provides arrays as primitive types actually. Arrays are denoted similarly to lists using particular brackets: | ||
| + | < | ||
| + | # [|1;2|];; | ||
| + | - : int array = [|1; 2|] | ||
| + | # | ||
| + | </ | ||
| + | As for lists, a map working on arrays is pre-defined: | ||
| + | < | ||
| + | # Array.map;; | ||
| + | - : ('a -> 'b) -> 'a array -> 'b array = <fun> | ||
| # | # | ||
| </ | </ | ||
magistraleinformaticanetworking/spm/ocamlfs1.txt · Ultima modifica: 23/03/2011 alle 16:31 (13 anni fa) da Marco Danelutto
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