Regression tests, would be hard to build any complex system without it

docs won't do anything about that type of problem

But in Clojure, I do not write tests to know code works, only tests to make sure public behaviour is never altered after release

And fuzz/generative tests, as a form of deep bug finding exercise

I've also found, component or mount, and the word state is confusing. State can be stored in a global Var/Atom/Ref or passed around from fn to fn. You only need component of mount if you're state needs to be initialized and cleaned up. So if a namespace needs a DB connection, expecting it to be connected already, with mount, you'd put a dependency on that "state", and mount will know to initialize it before giving it to you. But if by state, you mean just like running app state, like say I keep track of users created in a global Atom, the only need for mount/component, is to maybe clear the atom on reload, if I ever want too. But the value proposition is much less in this case.

Hello guys, is there a way how to reference other project files in project.clj? Say I have DB configuration in src/config/db_config.clj and I want to pass it to some lein plugin configuration. Thx for help 🙂

@petr.mensik You can use ~ in project.clj to cause evaluation of forms, so you could read the db_config.clj file that way... but I'm not sure I'd recommend that. You could join #leiningen and ask for more approaches there. We switched to #boot and found that much easier to use as a build tool for anything even vaguely complicated.

Can I use functions created with defn as helper functions to craft forms for defmacros. Say I have a list of symbols that I want to have a specific set of symbols output will it work in a reduce function or does it have to be a defmacro helper.

macros can call functions (or other functions) freely

just remember that the macro doesn’t see the actual data passed in at runtime, it only sees the form from the source code

as long as your function can do something useful with that, you are good to go

also, it’s good to distinguish a macro calling a function from a macro emitting a call to a function

right, that's still an exercise to wrap my head around.

I've got most of it but the macro is getting large and hard to follow, so didn't know how I should split it up

the thing that helped me most was focusing on the fact that a macro takes source code (in the form of symbols, lists etc, not a string) and returns the new source code to use in its place

The end part I can wrap my head around, emit symbols and it evaluates after macroexpansion. Actually crafting it is the hard part for me

as a beginner, one way to do that is often to make a function that just takes a form and returns a form (and break that down into more functions as needed) no macro definitions needed at any point there, and finally wrap a call to this function in a macro

breaking it up by writing functions that take code-data and return code-data to the macro is a good approach

@noisesmith that is definitely what I should have done, working to piece the whole is already taxing.

helps with repl testing too as you don't need to macroexpand all the time

switching to that approach is easy though

you can pretty much just take your defmacro, change it to defn, give it a new name, and now pass it quoted args as needed

Also how do I solve this issue. I'm appending to a form that needs to end up as

(do (ns some-ns) (print (escaped-form) ~(escaped-form))

first off, there’s no vectors there

right

that first one is after the conversion

oh sorry, now I get it

usually people use ~@ for that

(defmacro repl-step-do
  [time & forms]
  (reduce
   (fn [print-exprs [title & rest-forms]]
     (let [namespace (.toLowerCase (clojure.string/replace title " " "_"))
           form-exprs (conj (for [expr rest-forms]
                              ('print expr))
                            'do)]
       (-> print-exprs
           (conj `(ns ~(symbol namespace)))
           (conj form-exprs))))
   `[do]
   forms))

messy I know

so the ~@ version would be ````(do ~@(for [expr rest-forms] `(print ~expr)))```

I'm basically just creating a "slideshow" for repl blocks to easily run through an example for reference

I'm struggling with something really simple, hopefully you guys don't mind being asked a dumb question. I need to generate a game board, let's say a chess board, so I'm trying to create nested vectors like this: [[1 2 3 4][5 6 7 8][9 10 11 12][13 14 15 16]] I can't figure out how to generate something like that in a functional way

play with partition and range

(yeah, what @dpsutton said ^^ -- beat me to it!)

that should be enough to get you going. let us know if you run into anything or get stumped

also be mindful of your types (vector versus lazy lists) if that's important for you

Hint: you can get from a list of lists to a vector of vectors with (mapv vec ...)

That was super easy, thanks. Follow up question, say I didn't want those vectors to be contain numbers but something else (say a map at each location), still with the same structure of vectors though. Is range still the way to go? For example, this is what I have right now:

I don't need those id's in the map, that was just how I created the maps. I'm trying to create the 16 maps in that configuration and put some other stuff in there

repeat!

That solves it, thanks

@noisesmith how do you use clojurebot?

you don’t need the into calls if lists are OK

@hmaurer /clj (maybe buggy)

it barfs on strings for example

thanks!