Wow, I absolutely hated the C version of this.

Having the add function described in the AST description let me down a sidequest of trying to understand the strange structure of having add nodes AND str nodes. Took a while to realize add is just a helper function to append to a str linked list node.

Not to mention I thought I was supposed to implement the AST myself (which you sorta have to for testing). Looking at languages like rust it is immediately clear that it is an enum. In C its not so obvious from the start.

Perhaps some of these things could be added specifically to the C version's description (as I see a few other comments reflecting this opinion too, which is really what saved me).

it's not really an "issue" but a mistake people are likely to make, and that makes one scratch their head for a moment. what caused it for me was that in prototype methods, this always has type object, even for primitives (they are "boxed"), i.e. :

String.prototype.f = function () { console.log(typeof this); };
''.f(); // 'object', not 'string'

and assert.deepEqual(new String('abc'), 'abc'); fails (as it should, imo). but once stringified by chai, they look identical

What exactly causes the issue? Is it a type of the returned value being an iterator vs array? Maybe an explicit assertion on the expected type would help?

it'll be tough to fix since the stringification happens as one would expect, and I think deepEqual() failing is the right behavior. It was interesting to figure out what was happening too. I dont know what should be done here - a warning in the description ? a dedicated it() block with an helpful title ?

To anyone experiencing this, console.log your values instead and you'll probably figure out the quirk that's causing the comparison to fail

Not true aivenaut. You can try easily for yourself:

package main

import "fmt"

func x(slc []int) {
  slc[1] = 42
}

func main() {
  slc := []int{1,2,3}
  x(slc)
  fmt.Println(slc) // prints 1, 42, 3
}

You are correct that things are passed by value. But certain things are pointer types themselves without being a pointer. A slice is a structure with a size, a capacity, and an underlying array pointer. Even if you pass the slice as value, the underlying array is the same.

In golang when you pass a parameter to a function it will make a copy of it, unless pointer type is specified (eg arr *[]int). So this function is pure.

I was trying to get to this! I knew there had to be a one-liner with take_while. I didn't quite achieve it. Well done.

wtf! is this

yeah no you have to implement your own

Pretty fun kata with prior knowledge in crafting interpreters

It still happens with the Java random test.

Can someone please explain me this piece of code? what is id?

Good Kata. If you don't know what to do here, check out "Simplexer" first, since it teaches you the basics of Expression Parsing.