fv tests

--fvTest :: String -> [String] -> IO ()
makefvTest inp vars
    = TestCase (assertEqual ("for (fvs "++inp++")") (fvs inp) (sort vars))

--                   test expr.               expected result
testfv1 = makefvTest "x"                      ["x"]
testfv2 = makefvTest "let x = y in (+ x y)"   ["y"]
testfv3 = makefvTest "((fn x => (+ x y)) y)"  ["y"]
testfv4 = makefvTest fv4                     ["x","p"]
testfv5 = makefvTest fv5                     []
--own tests
testfv6 = makefvTest fv6 ["x"]
testfv7 = makefvTest fv7 ["y"]
testfv8 = makefvTest fv8 []

fv4 = "((fn p => (p x)) (fn x => (+ x p)))"
fv5 = "let c = fn x => fn p => (p (* x x)) in "
      ++ " (let inc = fn x => (+ 1 x) in (c 4 inc))"
fv6 = "let y = (+ y 3) in (+ x y)"
fv7 = "let x = (+ x y) in (let y = (+ y 1) in (let x = (+ 3 x) in (+ x y)))"
fv8 = "fn f => f (g x)"


-- the printed output of the follow looks horrible inside of emacs
runFvAll =  runTestTT $ TestList [ "Test 1" ~: testfv1
                                 , "Test 2" ~: testfv2
                                 , "Test 3" ~: testfv3
                                 , "Test 4" ~: testfv4
                                 , "Test 5" ~: testfv5
                                 , "Test 6" ~: testfv6  -- y is bound because it's named, but x isn't
                                 , "Test 7" ~: testfv7  -- x is bound to a definition, but y isn't
                                 , "Test 8" ~: testfv8] -- none of the variables are bound to a definition

subst tests

st14 = runSubst "let x = (* 7 4) in (- y 1)" "y" "(* 7 4)"
-- result: let a = (* 7 4) in (- (+ z 3) 1)
-- Substituting "y" for "(* 7 4)" in "let x = (* 7 4) in (- y 1)" yields
-- the given answer
st15 = runSubst "(y (x z))" "z" "fn z => (+ z 1)"
-- result: (y (x (fn z => (+ z 1))))
-- Substituting "fn z => (+ z 1)" for the variable "z" in "(y (x z))"
-- just means plugging the former into the latter
st16 = runSubst "fn x => (* x y)" "y" "x"
-- result: (fn a => (* x x))
-- Substituting "x" for "y" requires a new name for the function
-- to be determined with fresh, 'a'
-- e p x
-- e x p

runSubAll = do { st1; st2; st3; st4; st5; st6; st7; st8; st9; st10;
                 st11; st12; st13; st14; st15; st16
               }