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The existence rule type checks for the presence of specific tokens or patterns in your text. This is one of the simplest and most commonly used rule types in Vale.

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How It Works

The existence rule looks for any matches of specified tokens or regular expression patterns in the provided text. When a match is found, it triggers an alert.

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Parameters

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tokens
array
required
An array of strings or regular expressions to match against. Each token is treated as a separate pattern to look for.
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ignorecase
boolean
default:"true"
Makes all matches case-insensitive when set to true.
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nonword
boolean
default:"false"
Removes the default word boundaries (\b) when set to true. This allows you to match tokens that are part of larger words.
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exceptions
array
An array of strings or regex patterns to be ignored. Matches that are in the exceptions list will not trigger alerts.
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vocab
boolean
default:"true"
If true, Vale will use your vocabulary files (accept.txt) as additional exceptions.
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raw
array
An array of raw regex strings that will be concatenated directly into the pattern without modification.

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Examples

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Basic Word List

Check for overly technical acronyms that should be expanded: 
extends: existence
message: "Avoid using '%s'"
description: "Tech people know their acronyms; you come across as not very tech-savvy if you expand them."
ignorecase: true
level: warning
tokens:
  - 'cascading[ -]?style[ -]?sheets'
  - 'hyper[ -]?text([ -]?mark[ -]?up([ -]?language)?)?'

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E-Prime Style

Check for forms of “to be” to encourage more active writing: 
extends: existence
message: 'Avoid using "%s"'
ignorecase: true
level: suggestion
tokens:
  - am
  - are
  - aren't
  - be
  - been
  - being
  - is
  - isn't
  - was
  - wasn't
  - were
  - weren't

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Using Exceptions

Check for problematic terms while allowing specific exceptions: 
extends: existence
message: "Consider using '%s' instead of '%s'."
level: warning
ignorecase: false
tokens:
  - blacklist
  - whitelist
  - master
  - slave
exceptions:
  - Master's degree
  - masterpiece

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Pattern Matching with Nonword

Match patterns that aren’t complete words: 
extends: existence
message: "Don't use trailing punctuation in headings."
level: error
scope: heading
nonword: true
tokens:
  - '[a-z][.?!:,;]$'

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Use Cases

The existence rule is ideal for:
  • Maintaining word blocklists
  • Enforcing style guidelines about specific terms
  • Preventing deprecated terminology
  • Checking for brand name misuse
  • Enforcing inclusive language

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Technical Details

Internally, the existence rule (internal/check/existence.go:73-97):
  1. Compiles all tokens into a single regular expression pattern
  2. Searches the text for all matches using FindAllStringIndex
  3. For each match, checks if it’s in the exceptions list
  4. Creates an alert for any match that’s not an exception
The pattern compilation respects the ignorecase and nonword settings, automatically adding word boundaries unless nonword is true.
  • substitution: Use when you want to suggest replacements for matched tokens
  • occurrence: Use when you want to count how many times a token appears
  • repetition: Use when you want to detect repeated words

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