Validates that a value is strictly greater than a given reference value using an Ord comparator.

GreaterThan enforces an ordering constraint of the form: "value must be greater than X".

Ordering is defined by an Ord instance, not by numeric comparison or structural operators.

Options

• :value (required) The reference value to compare against.

• :ord (optional) An ordering comparator. Defaults to Funx.Ord.Protocol.

• :message (optional) A custom error message callback (value -> String.t()) used to override the default error message on failure.

Semantics

• If the value compares as :gt relative to the reference value under the given Ord, validation succeeds.
• If the value compares as :lt or :eq, validation fails.
• Nothing values are preserved and treated as not applicable.
• Just values are unwrapped before comparison.

Examples

iex> Funx.Validator.GreaterThan.validate(7, value: 5)
%Funx.Monad.Either.Right{right: 7}

iex> Funx.Validator.GreaterThan.validate("b", value: "a")
%Funx.Monad.Either.Right{right: "b"}

iex> Funx.Validator.GreaterThan.validate("a", value: "a")
%Funx.Monad.Either.Left{
  left: %Funx.Errors.ValidationError{
    errors: ["must be greater than \"a\""]
  }
}

iex> Funx.Validator.GreaterThan.validate(%Funx.Monad.Maybe.Nothing{}, value: 5)
%Funx.Monad.Either.Right{right: %Funx.Monad.Maybe.Nothing{}}