.filter is not a function
filter is a method on arrays. Since the code you posted contains an object, you’re seeing this error. You may want to apply filter after getting all the values from the object using Object.values, like this:
functional-programming
What tools are there for functional programming in C?
FFCALL lets you build closures in C — callback = alloc_callback(&function, data) returns a function pointer such that callback(arg1, …) is equivalent to calling function(data, arg1, …). You will have to handle garbage collection manually, though. Relatedly, blocks have been added to Apple’s fork of GCC; they’re not function pointers, but they let you pass around lambdas while avoiding the need to build … Read more
Reverse a list in haskell
You are separating the list into head and tail, but then re-assemble the list in the same order. Take the list [1, 2, 3] for example: In the first call, x will be 1, and xs will be [2, 3]. Then you create a new list, consisting of x (so 1) at the front, followed … Read more
Insertion sort in Haskell
is calling insert with three arguments (x,insertionSort,xs). Probably you want
What is the difference between procedural programming and functional programming?
A functional language (ideally) allows you to write a mathematical function, i.e. a function that takes n arguments and returns a value. If the program is executed, this function is logically evaluated as needed.1 A procedural language, on the other hand, performs a series of sequential steps. (There’s a way of transforming sequential logic into functional logic called continuation passing … Read more
What does Cons and :-: mean in Haskell?
I understand what most of this means apart from Cons. When I try :t Cons and :i Cons in ghci I get a not in scope error. You need to load the Haskell source file with the data declaration before you can have Cons in scope. Or, alternatively, you can enter that data line directly in GHCi. For serious code, it’s easier if you put it in … Read more
What is polymorphism in Javascript?
Polymorphism is one of the tenets of Object Oriented Programming (OOP). It is the practice of designing objects to share behaviors and to be able to override shared behaviors with specific ones. Polymorphism takes advantage of inheritance in order to make this happen. In OOP everything is considered to be modeled as an object. This … Read more
What’s the difference between lapply and do.call?
There is a function called Map that may be similar to map in other languages: lapply returns a list of the same length as X, each element of which is the result of applying FUN to the corresponding element of X. do.call constructs and executes a function call from a name or a function and a list of arguments … Read more
What is difference between functional and imperative programming languages?
Definition: An imperative language uses a sequence of statements to determine how to reach a certain goal. These statements are said to change the state of the program as each one is executed in turn. Examples: Java is an imperative language. For example, a program can be created to add a series of numbers: Each statement changes … Read more
Haskell pattern matching – what is it?
In a nutshell, patterns are like defining piecewise functions in math. You can specify different function bodies for different arguments using patterns. When you call a function, the appropriate body is chosen by comparing the actual arguments with the various argument patterns. Read A Gentle Introduction to Haskell for more information. Compare: with the equivalent Haskell: Note … Read more