How Try monad can be used in Groovy

TryMonadExample.groovy

import static java.lang.Integer.*
import static groovyfp.categories.Fn.*

def zero = { 0 }
def parse = { String c -> return { parseInt(c) } }
def addOne = { Integer y -> y + 1 }
def addToListIfValue =  { Integer z -> z ? List(z) : List() }

// Getting every item in the list
bind(List("2a","3","4")) { String x ->
    bind(
        recover(
            fmap(Try(parse(x)), addOne), // try to add one
            Try(zero) // get 0 in case of failure
        ),
        addToListIfValue // add partial result to a list
    )
}.typedRef.value

// Building what is going to be done per every item
def validNumbers = { String x ->
    bind( 
        recover(
            fmap(Try(parse(x)), addOne),
            Try(zero)
        ),
        addToListIfValue
    ).typedRef.value
}

def list = ["2a","3","4"]

// We are using collectMany method which flattens all
// nested list and ignore empty lists
def result = list.collectMany(validNumbers)