{-|
Module      : Core.Examples
Description : Core examples (may eventually be unit tests)
-}
{-# LANGUAGE QuasiQuotes #-}
{-# LANGUAGE OverloadedStrings #-}
module Core.Examples
    ( fac3
    , sumList
    , constDivZero
    , idCase
    ) where
----------------------------------------------------------------------------------
import Core.Syntax
import Core.TH
----------------------------------------------------------------------------------

-- fac3 = undefined
-- sumList = undefined
-- constDivZero = undefined
-- idCase = undefined

---

letrecExample :: Program'
letrecExample = [coreProg|
    pair x y f = f x y;

    fst' p = p k;
    snd' p = p k1;

    f x y =
        letrec
        { a = pair x b
        ; b = pair y a
        } in fst' (snd' (snd' (snd' a)));

    main = f 3 4;
|]

idExample :: Program'
idExample = [coreProg|
    main = id 3;
|]

indExample1 :: Program'
indExample1 = [coreProg|
    main = twice twice id 3;
|]

indExample2 :: Program'
indExample2 = [coreProg|
    main = twice twice twice id 3;
|]

indExample3 :: Program'
indExample3 = [coreProg|
    main = letrec
        { x = 2
        ; y = f x x
        } in g y y;

    f a b = b;
    g a b = a;
|]

negExample1 :: Program'
negExample1 = [coreProg|
    main = negate# (id 3);
|]

negExample2 :: Program'
negExample2 = [coreProg|
    main = negate# 3;
|]

negExample3 :: Program'
negExample3 = [coreProg|
    main = twice negate# 3;
|]

arithExample1 :: Program'
arithExample1 = [coreProg|
    main = (+#) 3 (negate# 2);
|]

arithExample2 :: Program'
arithExample2 = [coreProg|
    main = negate# ((+#) 2 ((*#) 5 3));
|]

ifExample1 :: Program'
ifExample1 = [coreProg|
    main = if# True 2 3;
|]

ifExample2 :: Program'
ifExample2 = [coreProg|
    main = if# (id True) 2 3;
|]

facExample :: Program'
facExample = [coreProg|
    fac n = if# ((==#) n 0) 1 ((*#) n (fac ((-#) n 1)));
    main = fac 3;
|]

pairExample1 :: Program'
pairExample1 = [coreProg|
    main = fst (snd (fst (MkPair (MkPair 1 (MkPair 2 3)) 4)));
|]

pairExample2 :: Program'
pairExample2 = [coreProg|
    main = (if# False fst snd) (MkPair 2 3);
|]

listExample1 :: Program'
listExample1 = [coreProg|
    main = caseList# (Cons 2 Nil) 3 k;
|]

listExample2 :: Program'
listExample2 = [coreProg|
    cc f x xs = Cons (f x) (map f xs);
    map f l = caseList# l Nil (cc f);
    list = Cons 1 (Cons 2 (Cons 3 Nil));
    main = map negate# list;
|]

listExample3 :: Program'
listExample3 = [coreProg|
    cc f z x xs = f x (foldr f z xs);
    foldr f z l = caseList# l z (cc f z);
    list = Cons 1 (Cons 2 (Cons 3 Nil));
    main = foldr (+#) 0 list;
|]

simple1 :: Program'
simple1 = [coreProg|
    k a b = a;
    s f g x = f x (g x);

    main = s k k 3;
|]

caseBool1 :: Program'
caseBool1 = [coreProg|
    _if c x y = case c of
        { 1 -> x
        ; 0 -> y
        };

    false = Pack{0 0};
    true = Pack{1 0};

    main = _if false ((+#) 2 3) ((*#) 4 5);
|]

fac3 :: Program'
fac3 = [coreProg|
    fac n = case (==#) n 0 of
        { 1 -> 1
        ; 0 -> (*#) n (fac ((-#) n 1))
        };

    main = fac 3;
|]

-- TODO: paramaterised examples? eg. sumList could take a haskell list of ints
-- as an input, translate it to a rl' list, and run the example on that?
sumList :: Program'
sumList = [coreProg|
        nil = Pack{0 0};
        cons x y = Pack{1 2} x y;
        list = cons 1 (cons 2 (cons 3 nil));
        sum l = case l of
            { 0      -> 0
            ; 1 x xs -> (+#) x (sum xs)
            };
        main = sum list;
    |]

constDivZero :: Program'
constDivZero = [coreProg|
        k x y = x;
        main = k 3 ((/#) 1 0);
    |]

idCase :: Program'
idCase = [coreProg|
        id x = x;

        main = id (case Pack{1 0} of
            { 1 -> (+#) 2 3
            })
    |]

-- corePrelude :: Module Name
-- corePrelude = Module (Just ("Prelude", [])) $
--     -- non-primitive defs
--     [coreProg|
--         id x = x;
--         k x y = x;
--         k1 x y = y;
--         s f g x = f x (g x);
--         compose f g x = f (g x);
--         twice f x = f (f x);
--         fst p = casePair# p k;
--         snd p = casePair# p k1;
--         head l = caseList# l abort# k;
--         tail l = caseList# l abort# k1;
--         _length_cc x xs = (+#) 1 (length xs);
--         length l = caseList# l 0 length_cc;
--     |]
--     <>
--     -- primitive constructors need some specialised wiring:
--     Program
--         [ ScDef "False" [] $ Con 0 0
--         , ScDef "True" [] $ Con 1 0
--         , ScDef "MkPair" [] $ Con 0 2
--         , ScDef "Nil" [] $ Con 1 0
--         , ScDef "Cons" [] $ Con 2 2
--         ]

--}