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June 28, 2017 01:24
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Week 2 - Functions Over Lists
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-module(functions_over_lists). | |
-export([product/1]). | |
-export([maximum/1]). | |
-export([product_fold/1]). | |
product(X) -> product(X, 1). | |
product([], Product) -> Product; | |
product([X | Xs], Product) -> product(Xs, X * Product). | |
product_fold(Xs) -> | |
lists:foldl(fun(X, P) -> X * P end, 1, Xs). | |
% Return 'none' for empty lists | |
maximum([]) -> none; | |
% Initialize Max to the first list item | |
maximum([X | Xs]) -> maximum(Xs, X). | |
% When all items are exhausted, return held Max | |
maximum([], Max) -> Max; | |
% Replace Max when a list item is a number and larger than the current Max | |
maximum([X | Xs], Max) when is_number(X), X > Max -> maximum(Xs, X); | |
% Otherwise continue on to the next item | |
maximum([_ | Xs], Max) -> maximum(Xs, Max). |
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