hvac-0.1: Http view and controller. A transactional, declarative framework for lightweight web applications. Contents Index

Network.Frameworks.HVAC.Validators Portability portable Stability experimental Maintainer s.clover@gmail.com

Description

Basic validators. You can write your own -- they're easy! Take a value, then fail with a useful error message or return a value, possibly the same, possibly transformed. That's it. Compose validators with Kleisi composition -- i.e., >=>. Validators may also perform nearly all HVAC operations that do not affect global state. For annoying reasons related to type-inference, they may not, however, access the session.

Synopsis

nonEmpty :: ValidationFunc s String String lengthAtLeast :: Int -> ValidationFunc s String String lengthUnder :: Int -> ValidationFunc s String String trim :: ValidationFunc s String String onNull :: String -> ValidationFunc s String String validEmail :: ValidationFunc s String String readValidated :: Read a => ValidationFunc s String a

Documentation

nonEmpty :: ValidationFunc s String String

Checks that the input is not empty. nonEmpty x = if null x then fail "No input." else return x

lengthAtLeast :: Int -> ValidationFunc s String String

Checks the input for minimum length.

lengthUnder :: Int -> ValidationFunc s String String

Checks the input for maximum length.

trim :: ValidationFunc s String String

Removes leading and trailing whitespace.

onNull :: String -> ValidationFunc s String String

Replaces empty input with a default value.

validEmail :: ValidationFunc s String String

Basic Email Validation Regex.

readValidated :: Read a => ValidationFunc s String a

readM specialized to the validation monad.

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