Dale libraries in Nix version

What happens?
I’m trying to use some libraries from the dale programming language to solve the codeabbey’s challenges. When I’ve imported the library that I guess I should use, the compiler throws an error message as follows:

What do you understand or find about that problem?

I don’t understand if I imported the correct library to get the code run successful they didn’t work.
I believe that there would be a misconfiguration on the Nix version of dale language that doesn’t allow to import the libraries accuratelly.

Did you try any workaround? What did you do?
I’ve been searching about the dale libraries within the dale repository in github.

I’ve also been looking for the library within the dale directory in my files system:

I’ve been trying to import all libraries and each one of them to run the code

(import cstdio)
(import cmath)
(import concepts-core)
(import concept-defs)
(import concepts)
(import enum)
(import derivations)
(import macros)
(import ctype)
(import utility)
(import drt)
(import cctype)
(import bitset-enum)
(import algorithms)
(import cstdlib)
(import list)
(import introspection)
(import map)
(import operator-macros)
(import pthread)
(import set)
(import shared-ptr)
(import stdlib)
(import unique-ptr)
(import unistd)
(import vector)
(import array)
(import arithmetic)
(import assert)
(import cerrno)
(import cfloat)
(import clocale)
(import csetjmp)
(import csignal)
(import math)
(import cstdio-arch)
(import cstdio-core)
(import cstring)
(import ctime)

    (def-variant Number ((Int    ((a int)))
                         (Float  ((a float)))))

    (def main (fn extern-c int (void)
      (let ((ni Number (Int 1))
            (nf Number (Float 2.0))
            (na (array-of 2 Number) (array ni nf)))
        (for (i \ 0) (< i 2) (incv i)
          (let ((nc Number (@$ na i)))
            (case nc
              (Int    (printf "Number is int (%d)\n"    (@:@ nc a)))
              (Float  (printf "Number is float (%f)\n"  (@:@ nc a)))))))
      0))

(import variant)

    (def-variant Number ((Int    ((a int)))
                         (Float  ((a float)))))

    (def main (fn extern-c int (void)
      (let ((ni Number (Int 1))
            (nf Number (Float 2.0))
            (na (array-of 2 Number) (array ni nf)))
        (for (i \ 0) (< i 2) (incv i)
          (let ((nc Number (@$ na i)))
            (case nc
              (Int    (printf "Number is int (%d)\n"    (@:@ nc a)))
              (Float  (printf "Number is float (%f)\n"  (@:@ nc a)))))))
      0))

Evidences
I’ve uploaded all the evidences before in this message

I need help with
To review if the Nix version of the Dale language have any lacks on its settings regarding to the libraries.

The version of dale that nix uses is the latest, so there is nothing I can do to fix this problem. Maybe many of those libraries are incompatible with the current version.

Regards,