YAML newbie help

[Tortue]

O Wise Ones, I've always though YAML was cool. But today I tried to actually use it for a quickie, and I realized it's not quite so easy. I'm looking for some documentation that can get me started real quick, with cut-and-pasteable practical examples. Please help me get past this kind of nonsense:

--- !perl/YAML::Error
code: YAML_PARSE_ERR_NO_SEPARATOR
msg: Expected separator '---'
line: 4
document: 2
...
 at test.pl line 20

At the main YAML site, I've seen the spec, the reference card, the Get Started, the faq. I've seen the module documentation. I've seen this nice article presenting YAML. I've searched this site. But it's all too advanced or too allusive for what I need.

[grinder]

I'm looking for some documentation that can get me started real quick, with cut-and-pasteable practical examples.

I've always found that the easiest way to write code to emit valid YAML is to create the target structure in Perl and dump it out, and look at the result.

#! /usr/local/bin/perl -w

use strict;
use YAML;

my $r = [
        1, 2, { a => [2, 3], b => [4, 5, 6] },
        { c => { d => 'd', e => 'e', f => [6, 7, 8] }, d => [10, 20, 3
+0] },
];

print YAML::Dump($r), "\n";

Which produces

---
- 1
- 2
- a:
    - 2
    - 3
  b:
    - 4
    - 5
    - 6
- c:
    d: d
    e: e
    f:
      - 6
      - 7
      - 8
  d:
    - 10
    - 20
    - 30

And from there it's pretty easy to whip up some code that produces this target output. From these sorts of empirical observations you can usually figure out what YAML you need to write to achieve the data structure you want to play with.

[zentara]

Here is a newbie tip:

The only thing I've ever needed to remember when using YAML is the syntax for dumping with better output.

#instead of
print Dump( %hash ),"\n";


#do

print Dump( [ \%hash ] ), "\n";

[PodMaster]

I'm looking for some documentation that can get me started real quick, with cut-and-pasteable practical examples

Everything you've references, the yaml site ... all fit the bill.

Please help me get past this kind of nonsense...

Why is that nonsense? It says you're missing '---' at some place, what exactly are you doing (where is the relevant code, sample data -- How (Not) To Ask A Question )?

[Tortue]

My humble apologies for wasting your time. How silly of me not to see that the answer was contained in my own question! I of course didn't mean the message was nonsense. I meant the nonsense was in my behavior. I foolishly thought there might be some list of examples like the Perl data structures cookbook, but for YAML, that my poor searching abilities hadn't uncovered. And that next time someone searched for YAML in this site, they'd be happy to find this node. I'll do penance for my presumption.

I'm sorry I wasn't more specific. My original, very trivial problem was to have a list of days, with for each day a team of people, and a head of a team.

By trial and error, I found this:

days:
 -
  date: 2005-06-01
  team:
   - Jack
   - Jill
   - Joe
  boss: Clara
 -
  date: 2005-06-02
  team:
    - Harry
    - Hillary
    - Howie
  boss: Victoria

It does the trick, producing an array of hashes of arrays. Now (does my greed know no bounds?) I'm wondering if there's a more concise way, so that team members could be on the same line. At the same time I feel shame to even mention it, because I'm sure the answer is in the fine documentation, and it's just my poor eyes that don't see it! But perhaps wisdom can be achieved through shame.

[Tortue]

Indeed, answering my own question after reading more of the long, but well-written specification: a more concise, but equivalent version, is of course:

 -
  date: 2005-06-01
  team: [ Jack, Jill, Joe ]
  boss: Clara
 -
  date: 2005-06-02
  team: [ Harry, Hillary, Howie ]
  boss: Victoria

Even more concise, each day can be made to fit on one line:

 - { date: 2005-06-01,  team: [ Harry, Hillary, Howie ],  boss: Clara 
+   }
 - { date: 2005-06-02,  team: [ Jack,  Jill,    Joe   ],  boss: Victor
+ia }

which makes it more readable as a table.

I wonder if you can simplify even further, by factoring out the hash keys? Something on the order of:

# INCORRECT YAML SYNTAX
 - { date:,      team:,                     boss:    }
 - { 2005-06-01, [ Harry, Hillary, Howie ], Clara    }
 - { 2005-06-02, [ Jack,  Jill,    Joe   ], Victoria }

Probably not.