All values in Python are references. What you need to worry about is if a type is mutable. The basic numeric and string types, as well as tuple and frozenset are immutable; names that are bound to an object of one of those types can only be rebound, not mutated. >>> t = 1, 2, … Read more
You should definitely check out http://research.microsoft.com/en-us/um/cambridge/projects/fsharp/manual/FSharp.PowerPack/Microsoft.FSharp.Collections.LazyList.html but I will try to post a more comprehensive answer later. UPDATE Ok, a solution is below. It represents the Morris sequence as a LazyList of LazyLists of int, since I presume you want it to be lazy in ‘both directions’. The F# LazyList (in the FSharp.PowerPack.dll) has three … Read more
Idiomatic Clojure favors defining independent functions that operate on a very small set of core data structures; this unbundling of methods and data is a strong statement against object orientation and in favour of a functional style. Rich Hickey (creator of Clojure) has repeatedly stated the importance of this; for example here: “Clojure eschews the … Read more
I think andih’s solution works great. Here is an alternate way because hey why not. It uses concat and distinct: user> (distinct (concat ‘(1 2 3) ‘(2 3 4))) => (1 2 3 4)
The OEIS now provides several points of access, not just ones using their internal format. These seem largely undocumented, so here are all of the endpoints that I have found: https://oeis.org/search?fmt=json&q=<sequenceTerm>&start=<itemToStartAt> Returns a JSON formatted response of the results found from the sequenceTerm given. If too many results were returned, count will be > 0 … Read more
There is no single interface for removing things from all of Clojure’s data structure types, possibly because of the different performance characteristics. (disj #{:foo :bar} :foo) ; => #{:bar} (dissoc {:foo 1 :bar 2} :foo) ; => {:bar 2} (pop [:bar :foo]) ; => [:bar] (pop (list :foo :bar)) ; => (:bar) These also work … Read more
Sql Server 2012 has introduced SEQUENCE objects, which allow you to generate sequential numeric values not associated with any table. Creating them are easy: CREATE SEQUENCE Schema.SequenceName AS int INCREMENT BY 1 ; An example of using them before insertion: DECLARE @NextID int ; SET @NextID = NEXT VALUE FOR Schema.SequenceName; — Some work happens … Read more
With a comprehension? Well… >>> seq = ‘012345’ >>> swapped_pairs = zip(seq[1::2], seq[::2]) >>> ”.join(item for pair in swapped_pairs for item in pair) ‘103254’
As Dennis Traub has pointed out, the overload of Aggregate you are using throws that exception when the source sequence is empty. The obvious fix is to use the other overload of Aggregate that accepts an initial seed (you want string.Empty), but that would result in a leading comma in the result which you’ll have … Read more
You are probably looking for the “drop” function known for example from from lodash: val seq = 1..10 seq.drop(5) > [6, 7, 8, 9, 10]