miniML

Implementation of miniML described in "Introduction to the theory of programming languages"(http://www.editions.polytechnique.fr/?afficherfiche=96, https://books.google.co.uk/books/about/Introduction_to_the_Theory_of_Programmin.html?id=hD7IEdT_6TYC&source=kp_cover&redir_esc=y&hl=en)

miniML is a minimalist language based on ML (https://en.wikipedia.org/wiki/ML_(programming_language)). The interpreter can run in either 'call by name' or 'call by value'.

Examples of miniML:

• The "let ... in" construct is used to define constants, the following evaluates to 21 (with v=1 and y=20):

let v=1 in let y=5+4*v in y+1

• Functions are defined like "fun a -> a + 1" and currying is used for multiple arguments:

fun a -> fun b -> b + a"

• The language doesn't have booleans, it uses a construct that tests if a value is 0: the following will evaluate to 1 if a is 0 and 2 if a is not 0

ifz a then 1 else 2

• Function applications are simply "function parameter", for example the following evaluates to 9

let f = fun a -> a * a in f 3

As miniML is not typed, the Y combinator (a function) can be used to implement recursive functions, like the factorial or the power function in the unit tests (more detailed explanation http://mvanier.livejournal.com/2897.html).

For example, the following expression evaluates to the factorial of 10:

let yComb = (fun f -> (fun x -> f (x x)) fun x -> f (x x)) in 
let iFact = fun f -> fun n -> ifz n then 1 else (n * (f (n-1))) in
(yComb iFact) 10

Still for convenience a 'fix' operator is included as it allows an easier to read syntax. The factorial of 10 can be computed using the following expression:

let fact = (fix f fun n -> (ifz n then 1 else (n * (f (n -1))))) in
fact 10