#+SETUPFILE: ~/.emacs.d/org-templates/level-2.org
#+HTML_LINK_UP: ../index.html
#+OPTIONS: toc:2
#+EXPORT_FILE_NAME: index
#+DATE: 2021-02-02
#+TITLE: Challenge 098

* Task 1 - Read N-characters
You are given file =$FILE=.

Create subroutine =readN($FILE, $number)= returns the first n-characters
and moves the pointer to the =(n+1)th= character.
** Raku
- Program: [[file:raku/ch-1.raku]]

=readN= is defined as such:
#+BEGIN_SRC raku
sub readN (
    IO $file, Int $chars --> Str
) {
    ...
}
#+END_SRC

The pointer index is stored in a state array (=%pointers=). It's stores
the pointer separately for each file. It's initialized with 0.
#+BEGIN_SRC raku
# %pointers stores the pointer index.
state Int %pointers;
%pointers{$file} = 0 without %pointers{$file};
#+END_SRC

The pointer is updated & required string is returned.
#+BEGIN_SRC raku
with %pointers{$file} -> $idx {
    %pointers{$file} += $chars;
    return $file.slurp.substr($idx, $chars);
}
#+END_SRC