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# bkhl's solution

## to ETL in the Perl 5 Track

Published at Sep 18 2019 · 0 comments
Instructions
Test suite
Solution

#### Note:

This exercise has changed since this solution was written.

We are going to do the `Transform` step of an Extract-Transform-Load.

### ETL

Extract-Transform-Load (ETL) is a fancy way of saying, "We have some crufty, legacy data over in this system, and now we need it in this shiny new system over here, so we're going to migrate this."

(Typically, this is followed by, "We're only going to need to run this once." That's then typically followed by much forehead slapping and moaning about how stupid we could possibly be.)

### The goal

We're going to extract some scrabble scores from a legacy system.

The old system stored a list of letters per score:

• 1 point: "A", "E", "I", "O", "U", "L", "N", "R", "S", "T",
• 2 points: "D", "G",
• 3 points: "B", "C", "M", "P",
• 4 points: "F", "H", "V", "W", "Y",
• 5 points: "K",
• 8 points: "J", "X",
• 10 points: "Q", "Z",

The shiny new scrabble system instead stores the score per letter, which makes it much faster and easier to calculate the score for a word. It also stores the letters in lower-case regardless of the case of the input letters:

• "a" is worth 1 point.
• "b" is worth 3 points.
• "c" is worth 3 points.
• "d" is worth 2 points.
• Etc.

Your mission, should you choose to accept it, is to transform the legacy data format to the shiny new format.

### Notes

A final note about scoring, Scrabble is played around the world in a variety of languages, each with its own unique scoring table. For example, an "E" is scored at 2 in the Māori-language version of the game while being scored at 4 in the Hawaiian-language version.

## Source

The Jumpstart Lab team http://jumpstartlab.com

## Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.

### etl.t

``````#!/usr/bin/env perl
use strict;
use warnings;

use Test2::Bundle::More;
use FindBin qw(\$Bin);
use lib \$Bin, "\$Bin/local/lib/perl5";
use ETL;

my @cases = (
{ old      => { 1 => ['A'] },
expected => { a => 1 },
name     => "transform one value"
},
{ old      => { 1 => [qw(A E I O U)] },
expected => { a => 1, e => 1, i => 1, o => 1, u => 1 },
name => "transform five values"
},
{ old => { 1 => [ 'A', 'E' ], 2 => [ 'D', 'G' ] },
expected => { a => 1, e => 1, d => 2, g => 2 },
name     => "transform a pair of values"
},
{ old => {
1  => [qw(A E I O U L N R S T)],
2  => [qw(D G)],
3  => [qw(B C M P)],
4  => [qw(F H V W Y)],
5  => ['K'],
8  => [qw(J X)],
10 => [qw(Q Z)]
},
expected => {
a => 1,
b => 3,
c => 3,
d => 2,
e => 1,
f => 4,
g => 2,
h => 4,
i => 1,
j => 8,
k => 5,
l => 1,
m => 3,
n => 1,
o => 1,
p => 3,
q => 10,
r => 1,
s => 1,
t => 1,
u => 1,
v => 4,
w => 4,
x => 8,
y => 4,
z => 10
},
name => "transform all values"
}
);

my \$module = 'ETL';

can_ok \$module, "transform"
or BAIL_OUT
"Missing package module \$module; or missing sub transform()";

my \$sub = \$module->can('transform');

foreach my \$c (@cases) {
is_deeply scalar \$sub->( \$c->{old} ), \$c->{expected}, \$c->{name};
}

done_testing();``````
``````package ETL;

use strict;
use warnings FATAL => 'all';

use Exporter qw(import);
our @EXPORT_OK = qw(score);

use List::Util qw(pairmap);

sub transform() {
my (\$input) = @_;

return scalar { pairmap { map {  lc \$_ => \$a } @\$b } %\$input };
}

1;``````