procedures.md

Topic	Procedures and partially applied function
Git sample	ProcedureTest.scala PartialAppliedFuncTest.scala
References	alvinalexander.com

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Procedures: methods with no return types

• A procedure is a Scala method or definition which Returns No Value. Because the procedure doesn’t return any value, It lacks equal(=) symbol

/* Look carefully: there is no '=' */
def box(s : String) { 

    val border = "-" * s.length + "--\n"
    println(border + "|" + s + "|\n" + border)
}

• If the function body is enclosed in braces without a preceding = symbol, then the return type is Unit

• Best is to always use Unitin cases where no return type

def box(s : String): Unit = {

}

Partial functions

• In Java all the parameters are passed to the function. In Scala you can give only a subset of the parameters to the function, the result of the expression is a partially applied function

def aFunction(one: Int, two: Int, three: Int) = one + two + three

/* A completly applied function */
val returnedValue = aFunction(1, 2, 3)
println(returnedValue)

/* A partial applied function */
val partialAppliedFunc = aFunction(1, _: Int, _: Int)
println(partialAppliedFunc)

/* A partial applied function */
val secondPartialAppliedFunc = aFunction(1, 2, _: Int)
println(secondPartialAppliedFunc)

/* A partial applied function */
val thirdPartialAppliedFunc = aFunction(1, _: Int, 3)
println(thirdPartialAppliedFunc)

/* Now apply all these functions on more variables */
println(partialAppliedFunc(2, 3))
println(secondPartialAppliedFunc(3))
println(thirdPartialAppliedFunc(2))