How to compose functions in Rust?

As @ljedrz points out, to make it work you only need to reference the composed functions again: let finally = compose(&*multiply_and_add, &*divide_and_subtract); (Note that in Rust, convention dictates that variable names should be in snake_case) However, we can make this better! Since Rust 1.26, we can use abstract return types (previously featured gated as #![feature(conservative_impl_trait)]). … Read more

What is “point free” style (in Functional Programming)?

Just look at the Wikipedia article to get your definition: Tacit programming (point-free programming) is a programming paradigm in which a function definition does not include information regarding its arguments, using combinators and function composition […] instead of variables. Haskell example: Conventional (you specify the arguments explicitly): sum (x:xs) = x + (sum xs) sum … Read more

How to understand curry and function composition using Lodash flow?

Silver Spoon Evaluation We’ll just start with tracing the evaluation of addSquare(3, 1) // … Ok, here goes = flow([add, trace(‘after add’), square]) (3, 1) add(3,1) 4 trace(‘after add’) (4) tap(x => console.log(`== ${ ‘after add’ }: ${ x }`)) (4) curry((interceptor, n) => { interceptor(n); return n; }) (x => console.log(`== ${ ‘after add’ … Read more

“Closures are poor man’s objects and vice versa” – What does this mean?

Objects are poor man’s closures. Consider Java. Java is an object-oriented programming language with no language level support for real lexical closures. As a work-around Java programmers use anonymous inner classes that can close over the variables available in lexical scope (provided they’re final). In this sense, objects are poor man’s closures. Closures are poor … Read more