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diff --git a/yaml.html.markdown b/yaml.html.markdown new file mode 100644 index 00000000..c5d15895 --- /dev/null +++ b/yaml.html.markdown @@ -0,0 +1,139 @@ +--- +language: yaml +filename: learnyaml.yaml +contributors: + - ["Adam Brenecki", "https://github.com/adambrenecki"] +--- + +YAML is a data serialisation language designed to be directly writable and +readable by humans. + +It's a strict superset of JSON, with the addition of syntactically +significant newlines and indentation, like Python. Unlike Python, however, +YAML doesn't allow literal tab characters at all. + +```yaml +# Comments in YAML look like this. + +################ +# SCALAR TYPES # +################ + +# Our root object (which continues for the entire document) will be a map, +# which is equivalent to a dictionary, hash or object in other languages. +key: value +another_key: Another value goes here. +a_number_value: 100 +scientific_notation: 1e+12 +boolean: true +null_value: null +key with spaces: value +# Notice that strings don't need to be quoted. However, they can be. +however: "A string, enclosed in quotes." +"Keys can be quoted too.": "Useful if you want to put a ':' in your key." + +# Multiple-line strings can be written either as a 'literal block' (using |), +# or a 'folded block' (using '>') +literal_block: | + This entire block of text will be the value of the 'literal_block' key, + with line breaks being preserved. + + The literal continues until de-dented, and the leading indentation is + stripped. + + Any lines that are 'more-indented' keep the rest of their indentation - + these lines will be indented by 4 spaces. +folded_style: > + This entire block of text will be the value of 'folded_style', but this + time, all newlines will be replaced with a single space. + + Blank lines, like above, are converted to a newline character. + + 'More-indented' lines keep their newlines, too - + this text will appear over two lines. + +#################### +# COLLECTION TYPES # +#################### + +# Nesting is achieved by indentation. +a_nested_map: + key: value + another_key: Another Value + another_nested_map: + hello: hello + +# Maps don't have to have string keys. +0.25: a float key + +# Keys can also be multi-line objects, using ? to indicate the start of a key +? | + This is a key + that has multiple lines +: and this is its value + +# YAML also allows collection types in keys, but many programming languages +# will complain. + +# Sequences (equivalent to lists or arrays) look like this: +a_sequence: + - Item 1 + - Item 2 + - 0.5 # sequences can contain disparate types + - Item 4 + - key: value + another_key: another_value + - + - This is a sequence + - inside another sequence + +# Since YAML is a superset of JSON, you can also write JSON-style maps and +# sequences: +json_map: {"key": "value"} +json_seq: [3, 2, 1, "takeoff"] + +####################### +# EXTRA YAML FEATURES # +####################### + +# YAML also has a handy feature called 'anchors', which let you easily duplicate +# content across your document. Both of these keys will have the same value: +anchored_content: &anchor_name This string will appear as the value of two keys. +other_anchor: *anchor_name + +# YAML also has tags, which you can use to explicitly declare types. +explicit_string: !!str 0.5 +# Some parsers implement language specific tags, like this one for Python's +# complex number type. +python_complex_number: !!python/complex 1+2j + +#################### +# EXTRA YAML TYPES # +#################### + +# Strings and numbers aren't the only scalars that YAML can understand. +# ISO-formatted date and datetime literals are also parsed. +datetime: 2001-12-15T02:59:43.1Z +datetime_with_spaces: 2001-12-14 21:59:43.10 -5 +date: 2002-12-14 + +# The !!binary tag indicates that a string is actually a base64-encoded +# representation of a binary blob. +gif_file: !!binary | + R0lGODlhDAAMAIQAAP//9/X17unp5WZmZgAAAOfn515eXvPz7Y6OjuDg4J+fn5 + OTk6enp56enmlpaWNjY6Ojo4SEhP/++f/++f/++f/++f/++f/++f/++f/++f/+ + +f/++f/++f/++f/++f/++SH+Dk1hZGUgd2l0aCBHSU1QACwAAAAADAAMAAAFLC + AgjoEwnuNAFOhpEMTRiggcz4BNJHrv/zCFcLiwMWYNG84BwwEeECcgggoBADs= + +# YAML also has a set type, which looks like this: +set: + ? item1 + ? item2 + ? item3 + +# Like Python, sets are just maps with null values; the above is equivalent to: +set2: + item1: null + item2: null + item3: null +``` |