YAML

hugo/content/posts/2024-03-14-yaml-superset-json.md

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+---
+lastmod: "2024-04-14T00:12:00.0000000+00:00"
+author: patrick
+date: "2024-03-14T00:12:00.0000000+00:00"
+title: YAML is not a superset of JSON
+summary: "All the reasons I know for why YAML is not a superset of JSON."
+categories:
+- programming
+---
+
+I keep forgetting, so here we go.
+Please let me know if you have any others!
+
+## Treatment of e.g. `1e2`
+
+JSON treats the value `1e2` a number, of course, because it's not in quote marks.
+YAML fails to parse it as a number so silently falls back to treating it as a string.
+
+```python
+>>> import yaml
+>>> import json
+
+>>> yaml.safe_load('{"a": 1e2}')
+{'a': '1e2'}
+
+>>> json.loads('{"a": 1e2}')
+{'a': 100.0}
+```
+
+## Tabs as indentation
+
+YAML does not permit tabs to be used as indentation.
+
+```python
+>>> yaml.load ('{\n  "list": [\n    {},\n\t{}\n    ]\n}')
+# yaml.scanner.ScannerError: while scanning for the next token
+# found character '\t' that cannot start any token
+
+>>> json.loads('{\n  "list": [\n    {},\n\t{}\n    ]\n}')
+{'list': [{}, {}]}
+```