allow_null              Allow NULL
as_contract_block       Convert a Validator to a Multi-Line Block
as_contract_text        Convert a Validator to Plain Text
expect_invalid          Expect a Value to Fail a Validator
expect_valid            Expect a Value to Pass a Validator
fail                    Format a Validation Error
is_valid                Test Whether a Value Satisfies a Validator
require_any             Require at Least One of Several Validators
require_between         Require Value in Range
require_character       Require Character Type
require_class           Require a Specific Class
require_col             Validate a Data Frame Column with a Validator
require_contains        Require All of a Set of Values
require_custom          Create a Custom Validation Step
require_df              Require a Data Frame
require_dim             Require Exact Dimensions
require_dir_exists      Require Existing Directories
require_disjoint        Require Values Disjoint From Context
require_each            Validate Every Element of a List
require_fields          Validate Named Fields of a List
require_file_exists     Require Existing Files
require_finite          Require Finite Values
require_function        Require a Function
require_has_cols        Require Specific Columns
require_integer         Require Integer Values
require_length          Require Specific Length
require_length_matches
                        Require Length Matching an Expression
require_length_max      Require Maximum Length
require_length_min      Require Minimum Length
require_levels          Require Factor Levels
require_logical         Require Logical Type
require_named           Require Named Value
require_names           Require Names
require_nchar           Require String Length
require_ncol_matches    Require Column Count Matching an Expression
require_ncol_min        Require Minimum Number of Columns
require_negative        Require Negative Values
require_no_na           Require No NA Values
require_nonempty        Require Non-Blank Strings
require_not_null        Require Non-NULL Value
require_nrow_matches    Require Row Count Matching an Expression
require_nrow_min        Require Minimum Number of Rows
require_numeric         Require Numeric Type
require_one_of          Require Value from a Set
require_pattern         Require Strings Matching a Pattern
require_positive        Require Positive Values
require_readable        Require Readable Paths
require_scalar          Require Scalar Value
require_set_equal       Require the Same Set of Values
require_sorted          Require Sorted Values
require_unique          Require Unique Values
require_unique_names    Require Unique Names
require_valid           Include Another Validator's Steps
require_writable        Require Writable Paths
restrict                Create a Composable Validator
steps                   List the Steps of a Validator
validation_errors       Collect Validation Errors Without Throwing
