2017年2月9日 · For this reason, SML programmers sometimes write function which create lists in a backwards order (appending to the front rather than the back, even in situations where appending to the back seems more natural) and then run the resulting list through rev (which is implemented in a clever way so that it is O(n)) to get the desired list.

2011年12月18日 · List.nth is part of the Standard ML Basis Library; it maps from 'a list * int to 'a. In this case List.nth (myList, 0) is (1,9,3) . (Note that it uses zero-based indexing.) #2 is a built-in part of the language, referring to the 2 -labeled component of a record (such as, as in this case, the second component of a tuple).

2012年9月8日 · Looks like you've just got your types wrong. A list has to be a list of something (e.g. an int list). If the type of the contents is irrelevant, you can use a type variable 'a instead of a concrete type (so in your case, an 'a list and an 'a list list). However, you almost never need type declarations in ML.

2013年1月20日 · I have learned some of the List functions. "List.nth" is one of them. When I use this function in SML command window, It is working fine. But when used inside Let..in..end; block , It is not working. I hope, Somebody would be able to help out. let val actualDays = 0; in actualDays = List.nth([10,20,31,50,45], 2); actualDays end; Expected output:

2017年4月24日 · I need to write an SML function that takes in as input a list of tuples (x and y coordinates) and an integer value. The function needs to return true if the integer is an x value in the list and false otherwise. For example if the list was: val list = [(1,1),(2,4),(3,9),(4,16)]; The function would behave as follows:

I'm very new to SML and I am trying a list exercise. The goal is sum up the previous numbers of a list and create a new list. For example, an input list [1, 4, 6, 9] would return [1, 5, 11, 20]. This is my solution so far, but I think the issue is with how I'm defining the function.

2023年9月28日 · Here is the general idea - it is very straightforward to translate into SML: The sum of a list is. If the list is empty, it is zero; Otherwise, add the head of the list to the sum of the tail of the list. Note that there are no variables and no assignments anywhere.

2013年1月19日 · There is no sorting functionality defined in the SML Basis Library, but most implementations extend the basis library and add extra functionality. As such MosML has both an ArraySort and a Listsort module, and SML/NJ has a LIST_SORT signature with a ListMergeSort implementation. It also features some other sorting features on arrays as MosML.

2011年11月26日 · I suspect the problem is not with your list printing code - that's going to work fine, provided it is called with some data. For reference, there's a nicer way to evaluate for effects with lists: List.app : ('a -> unit) -> 'a list -> unit. It's like List.map, but it doesn't construct a list as a

2010年11月23日 · I am trying to do basic list operations with SML. I want to extract each element of the list and append string to that element and add it back to the list.