grades.p6

#!/usr/bin/env perl6

my %grade = "grades.txt".IO.lines.map: {
    m:s/^ (\w+) (<[A..F]><[+-]>?) $/ or die "Can't parse line '$_'";
    ~$0 => ~$1
};

say "Zsófia's grade: %grade<Zsófia>";

say "List of students with a failing grade:";
say "  " ~ %grade.grep(*.value ge "E")».key.join(', ');

say "Distribution of grades by letter:";
say "  {.key}: {+.value} student{"s" if .value != 1}"
    for %grade.classify(*.value.comb[0]).sort(*.key);

grades.pl

#!/usr/bin/env perl

use warnings;
use strict;
use feature 'say';
use utf8;
binmode STDOUT, ":utf8";

open my $fh, '<:utf8', "grades.txt" or die "Failed to open file: $!";
my %grade;

while (<$fh>) {
    m/^ (\w+) \s+ ([A-F][+-]?) $/x or die "Can't parse line '$_'";
    $grade{$1} = $2;
};

say "Zsófia's grade: $grade{Zsófia}";

say "List of students with a failing grade:";
say "  " . join ", ", grep { $grade{$_} ge "E" } keys %grade;

say "Distribution of grades by letter:";
my %freq;
$freq{substr $grade{$_}, 0, 1}++ for keys %grade;
say "  $_: $freq{$_} student".($freq{$_} != 1 ? "s" : "")
    for sort keys %freq;

grades.txt

Peter	B
Celine	A-
Zsófia	B+
João	F
Maryam	B+
秀英	B-
Finn	D+
Aarav	A
Emma	F
Omar	B

grades_rakudofix.p6

#!/usr/bin/env perl6

my %grade = "grades.txt".IO.lines.map: {
    m:s/^ (\w+) (<[A..F]><[+-]>?) $/ or die "Can't parse line '$_'";
    ~$0 => ~$1
};

say "Zsófia's grade: %grade<Zsófia>";

say "List of students with a failing grade:";
say "  " ~ %grade.grep(*.value ge "E")».key.join(', ');

say "Distribution of grades by letter:";
say "  $(.key): $(+.value) student$("s" if .value != 1)"
    for %grade.classify(*.value.comb[0]).sort(*.key);