Prelude

The Prelude must imported to access the library types and functions.

import io.hascalator._
import Prelude._

id: the identity function, useful as placeholder when an high order function is needed but no meaningful option exists.

scala> id(42)
res0: Int = 42

scala> List(1, 2, 3).map(id)
res1: io.hascalator.data.List[Int] = [1, 2, 3]

const: is a unary function which evaluates to x for all inputs.

scala> List(0, 1, 2, 3).map(const(42))
res2: io.hascalator.data.List[Int] = [42, 42, 42, 42]

flip: takes its (first) two arguments in the reverse order of f.

scala> val f = (a: String, b: String) => a + " " + b
f: (io.hascalator.Prelude.String, io.hascalator.Prelude.String) => String = <function2>

scala> f("hello", "world")
res3: String = hello world

scala> f.flip("hello", "world")
res4: String = world hello

until yields the result of applying f until the predicate holds.

scala> until[Int](_ > 10)(_ + 1)(0)
res5: io.hascalator.Prelude.Int = 11

Numeric functions

even checks whether the argument is an even number

scala> even(42)
res6: io.hascalator.Prelude.Boolean = true

scala> even(43)
res7: io.hascalator.Prelude.Boolean = false

odd checks whether the argument is an odd number

scala> odd(42)
res8: io.hascalator.Prelude.Boolean = false

scala> odd(43)
res9: io.hascalator.Prelude.Boolean = true

gcd: gcd(x, y) is the non-negative factor of both x and y of which every common factor of x and y is also a factor:

scala> gcd(4, 2)
res10: Int = 2

scala> gcd(-4, 6)
res11: Int = 2

scala> gcd(0, 0)
res12: Int = 0