[2020-08-28] An example that will not compile in ytt.

array-literals-error.yml

#@ def yml_array_literal1():
  - a
  - b
#@ end

#@ def yml_array_literal2():
 - 1
 - 2
#@ end
---
ymlkey1: #@ yml_array_literal1()
ymlkey2: #@ yml_array_literal2()

The YAML fragments are at different indentation levels, and will not compile.

Returns the error:

Unmarshaling YAML template 'array-literals-error.yml': yaml: line 6: did not find expected <document start>

To fix, a document separator can be used between the 2 function defs, or they can share the same indentation level.