An error of the parser or the decoder.

An error from the functions of this module keeps no part of the input alive once it is in weak head normal form. Its message and its path are evaluated then, because a message often contains a slice of the input, e.g. a key, and a path comes from the syntax tree.

A position in the input. Lines and columns count from 1, and a column counts characters, not bytes. Line 0 and column 0 mean that the error has no position, e.g. because it comes from a node that a program built, or from a parsed node that is decoded without its input.

The keys and the indices from the root of a document to a node.

The path of a node shares the path of its parent, so the paths of many errors in a deep document take memory linear in its size.

The steps of a path, from the root.

A path with the steps from the root.

A step of a path into a document.

Render an error in the format that editors recognize. The result does not end with a line break. If the line is longer than 80 characters, the excerpt shows only the 80 characters around the column. A control character other than a tab shows as its symbol, e.g. U+241B for escape, or as U+FFFD if Unicode has no symbol for it.

>>> either printErrors print (decodeText @(M.Map T.Text [[Int]]) "jobs:\n  - [1]\n  - 42\n")
input.yaml:3:5: jobs[1]: expected a list, but got an integer
  |
3 |   - 42
  |     ^

An error with no position gives only the file and the message, e.g. input.yaml: duplicate key "a".

A path in the form jobs[1].name. A key that is a collection is ?, and a key that is an alias is its alias, e.g. *base.

A key is in double quotes, e.g. "a.b", if it:

• is empty,
• has white space, a character that cannot be printed, or one of the characters .[]"\,
• starts with ? or *.

In the quotes, a character that cannot be printed has an escape as in YAML, e.g. "a\nb".

>>> renderPath (pathFromElements [Key "jobs", Index 1, Key "name"])
"jobs[1].name"

>>> renderPath (pathFromElements [Key "a.b", Key ""])
"\"a.b\".\"\""

Create an error at the given offset of the input.

Create errors at the given offsets of the input, in the order of the list. One scan of the input locates all of them, and the errors on one line share the copy of the line.

Create errors at the given offsets of a document, with their paths, in the order of the list. The text is the input of the document, e.g. for the offsets of Located values.

Compute the line and the column of an offset. The byte order marks at the start of a line are not columns, because they are not content. For noOffset or an offset beyond the end of the input, the line and the column are 0.

The path from the root to the node at the offset. If several nodes start there, e.g. a block mapping and its first key, the outermost one counts. A key does not add to the path, and a node inside a key that is a collection has the path of the mapping.

The paths of nodePath for several offsets, in the order of the offsets, from one walk of the tree.