3 ms·

appear incredibly simple*️

mikekchar 9y ago
In what way is it not simple? It's hard to tell what you mean. The syntax is actually a bit of a nightmare if you are writing a parser, but from the perspective of a human reader, it shows you exactly what's going on under the hood.
- agumonkey 9y ago
  I think, as others above, parent meant to say "simple to write but not to use".
  - mikekchar 9y ago
    Hmm... One way that I find easier to understand partial application is to imagine that it's an object. All of the bound variables are like instance variables in the object. Imagine that you have a collection of items that you want to map over. Unfortunately the function you want to run takes 2 parameters instead of one. What if that function was really an object with one instance variable and a method that took 1 variable. So something like this (if it formats correctly): class Person { constructor(name) { this.name = name; } is(adj) { console.log(this.name + ' is ' + adj); } }; const mike = new Person('Mike'); ['smart', 'handsome'].forEach((adj) => mike.is(adj)); I think most people from an object oriented background will find this easy to understand. Instead of making an object, though, we can just make a function that binds the value in conceptually the same way: const is = name => adj => { console.log(name + " is " + adj); } const mikeIs = is('Mike'); ['smart', 'handsome'].forEach(mikeIs); Note: I don't have to make a lambda in the second case because I don't have to trip over `this` pointers, but I could if I wanted: ['smart', 'handsome'].forEach((adj) => mikeIs(adj)); Now, imagine that you have a bunch of curried functions, whose first argument is "name". Let's say "is", "jumps", "eats". You could write a function like this: const Person = (name) => { return { is: is(name), jumps: jumps(name), eats: eats(name) }; }; This is literally a class (minus the crazy `this` pointers). This is one of the reasons, I really like Javascript. :-)
    - agumonkey 9y ago
      One major difference though, objects with multiple fields will require some sophisticated logic to ensure correct order of initialization (depending on the way constructors and setters are done). A partial function enforces some order. You can accumulate safely information and get closer to a usable and valid final piece of logic. It's less easy when you need choice although one can use subfunctions . In OOP you may have fluent interfaces, builder things but it's.. once again a lot for not much more.

In what way is it not simple? It's hard to tell what you mean. The syntax is actually a bit of a nightmare if you are writing a parser, but from the perspective of a human reader, it shows you exactly what's going on under the hood.

agumonkey 9y ago
I think, as others above, parent meant to say "simple to write but not to use".
- mikekchar 9y ago
  Hmm... One way that I find easier to understand partial application is to imagine that it's an object. All of the bound variables are like instance variables in the object. Imagine that you have a collection of items that you want to map over. Unfortunately the function you want to run takes 2 parameters instead of one. What if that function was really an object with one instance variable and a method that took 1 variable. So something like this (if it formats correctly): class Person { constructor(name) { this.name = name; } is(adj) { console.log(this.name + ' is ' + adj); } }; const mike = new Person('Mike'); ['smart', 'handsome'].forEach((adj) => mike.is(adj)); I think most people from an object oriented background will find this easy to understand. Instead of making an object, though, we can just make a function that binds the value in conceptually the same way: const is = name => adj => { console.log(name + " is " + adj); } const mikeIs = is('Mike'); ['smart', 'handsome'].forEach(mikeIs); Note: I don't have to make a lambda in the second case because I don't have to trip over `this` pointers, but I could if I wanted: ['smart', 'handsome'].forEach((adj) => mikeIs(adj)); Now, imagine that you have a bunch of curried functions, whose first argument is "name". Let's say "is", "jumps", "eats". You could write a function like this: const Person = (name) => { return { is: is(name), jumps: jumps(name), eats: eats(name) }; }; This is literally a class (minus the crazy `this` pointers). This is one of the reasons, I really like Javascript. :-)
  - agumonkey 9y ago
    One major difference though, objects with multiple fields will require some sophisticated logic to ensure correct order of initialization (depending on the way constructors and setters are done). A partial function enforces some order. You can accumulate safely information and get closer to a usable and valid final piece of logic. It's less easy when you need choice although one can use subfunctions . In OOP you may have fluent interfaces, builder things but it's.. once again a lot for not much more.