6 files changed, 120 insertions, 1 deletions
diff --git a/entries/funemy/.gitignore b/entries/funemy/.gitignore
index acb903a..9211bbd 100644
--- a/entries/funemy/.gitignore
+++ b/entries/funemy/.gitignore
@@ -1,3 +1,6 @@
 .DS_Store
 *.agdai
 *.smt2
+**/.koka/*
+*.hi
+*.o
diff --git a/entries/funemy/haskell/morphib.hs b/entries/funemy/haskell/morphib.hs
new file mode 100644
index 0000000..1fae449
--- /dev/null
+++ b/entries/funemy/haskell/morphib.hs
@@ -0,0 +1,43 @@
+-- Fantastic Morphisms
+newtype Free f = Free {unFree :: f (Free f)}
+
+cata :: Functor f => (f a -> a) -> Free f -> a
+cata phi (Free x) = phi $ fmap (cata phi) x
+
+ana :: Functor f => (a -> f a) -> a -> Free f
+ana phi x = Free $ fmap (ana phi) (phi x)
+
+data FibF a =
+      Fib0
+    | Fib1
+    | FibN a a
+    deriving (Eq, Show)
+
+instance Functor FibF where
+    fmap f Fib0       = Fib0
+    fmap f Fib1       = Fib1
+    fmap f (FibN l r) = FibN (f l) (f r)
+
+type Fib a = Free FibF
+
+gen :: Int -> FibF Int
+gen 0 = Fib0
+gen 1 = Fib1
+gen n = FibN (n-1) (n-2)
+
+interp :: FibF Int -> Int
+interp Fib0       = 0
+interp Fib1       = 1
+interp (FibN l r) = l + r
+
+bif :: Int -> Fib Int
+bif = ana gen
+
+fib' :: Fib Int -> Int
+fib' = cata interp
+
+fib :: Int -> Int
+fib = fib' . bif
+
+main :: IO ()
+main = print (fib 14)
diff --git a/entries/funemy/koka/fib.kk b/entries/funemy/koka/fib.kk
new file mode 100644
index 0000000..5b7e66b
--- /dev/null
+++ b/entries/funemy/koka/fib.kk
@@ -0,0 +1,12 @@
+effect fib
+  ctl fib(n : int) : int
+
+fun doFib(inp : int) : div int
+  with ctl fib(n)
+    if n == 0 then 0
+    else if n == 1 then 1
+    else (doFib(n - 1) : int) + doFib(n - 2)
+  fib(inp)
+
+fun main()
+  print(doFib(20))
diff --git a/entries/funemy/symbolic/phib.py b/entries/funemy/symbolic/phib.py
new file mode 100644
index 0000000..c6fb23e
--- /dev/null
+++ b/entries/funemy/symbolic/phib.py
@@ -0,0 +1,21 @@
+from typing import List
+ 
+def phib(xs: List[int]) -> bool:
+    """
+    Instructions:
+        1. `pip install crosshair-tool`
+        2. modify the precondition `pre` to control the length of your fib sequence
+        3. run `crosshair check phib.py` in your terminal
+
+    pre: len(xs) >= 10
+    post: __return__ != True
+    """
+    if xs[0] != 0:
+        return False
+    if len(xs) > 1:
+        if xs[1] != 1:
+            return False
+        for i in range(2,len(xs)):
+            if xs[i] != xs[i-1] + xs[i-2]:
+                return False
+        return True
diff --git a/entries/funemy/z3/z3fib.sh b/entries/funemy/z3/z3fib.sh
index 07ab418..e96226f 100755
--- a/entries/funemy/z3/z3fib.sh
+++ b/entries/funemy/z3/z3fib.sh
@@ -15,7 +15,7 @@ else
 fi
 
 if [ "$1" -lt "0" ]; then
-  echo "Argument must be larger than 0."
+  echo "Argument must be larger or equal to 0."
   exit 1
 fi
 
diff --git a/entries/funemy/z3/z4fib.sh b/entries/funemy/z3/z4fib.sh
new file mode 100755
index 0000000..f7a1e48
--- /dev/null
+++ b/entries/funemy/z3/z4fib.sh
@@ -0,0 +1,40 @@
+#!/bin/bash
+# z3 fib, but better
+
+# Instructions:
+#  1. having z3 installed and put under your $PATH
+#  2. making sure z4fib.sh is executable, by `chmod +x z4fib.sh`
+#  3. running as `./z4fib.sh [length of the fib sequence]`
+#  4. having fun :)
+
+if [ -e fib.smt2 ]
+then
+    rm -f fib.smt2
+    touch fib.smt2
+else
+    touch fib.smt2
+fi
+
+if [ "$1" -lt "0" ]; then
+  echo "Argument must be larger or equal to 0."
+  exit 1
+fi
+
+echo "(declare-const fib (Seq Int))" >> fib.smt2
+echo "" >> fib.smt2
+echo "(assert" >> fib.smt2
+echo "  (and" >> fib.smt2
+echo "    (= (seq.len fib) $1)" >> fib.smt2
+echo "    (= (seq.nth fib 0) 0)" >> fib.smt2
+echo "    (= (seq.nth fib 1) 1)" >> fib.smt2
+echo "    (forall ((i Int))" >> fib.smt2
+echo "      (=> (and (> i 1) (< i (seq.len fib)))" >> fib.smt2
+echo "        (= (seq.nth fib i)" >> fib.smt2
+echo "          (+ (seq.nth fib (- i 1))" >> fib.smt2
+echo "            (seq.nth fib (- i 2))))))))" >> fib.smt2
+echo "" >> fib.smt2
+
+echo "(check-sat)" >> fib.smt2
+echo "(get-model)" >> fib.smt2
+
+z3 fib.smt2