1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53

//! Rust has really powerful generics that can be used to make it more functional in terms of it's
//! composition. Included in this crate are helper functions often times used in languages like
//! Haskell.
#![allow(dead_code)]
extern crate kinder;
pub mod list;

// ReExporting traits for various stdlib items so that they can be used implicitly
pub use std::iter::FromIterator;

/// Given a Tuple return it's first element
pub fn fst<A,B>(x:(A,B)) -> A {
    x.0
}

/// Given a Tuple return it's second element
pub fn snd<A,B>(x:(A,B)) -> B {
    x.1
}

/// Given a value return itself. This is like the mathematical identity function
pub fn identity<A>(x:A) -> A {
    x
}

/// Works like Haskell's bool, this is a way to do an inline if then else statement
/// if b then x else y
pub fn ifte<A>(x: A, y: A, b:bool) -> A {
    if b { x } else { y }
}

#[test]
fn fst_works() {
    assert_eq!(fst((1,"Hello")),1);
}

#[test]
fn snd_works() {
    assert_eq!(snd((1,"Hello")),"Hello");
}

#[test]
fn identity_works() {
    assert_eq!(identity(1), 1);
    assert_eq!(identity(1.0), 1.0);
    assert_eq!(identity("Hi"), "Hi");
}

#[test]
fn ifte_works() {
    assert_eq!(ifte("Hi","Bye", true), "Hi");
    assert_eq!(ifte("Hi","Bye", false), "Bye");
}