------------------------- if then else -----------------------
--------------------------- correct -------------------------

if (head [True, False]) then "true" else ['t','r', 'u', 'e']
if (head [True, False]) then 1 else 0 
if True then 1 else 0
if True then (head [True, False]) else False
if True then True else (head [False, True])
if True then "true" else ['t','r', 'u', 'e']

------------------------- if then else -----------------------
--------------------------- wrong -------------------------

if (head (False, True)) then "true" else ['t','r', 'u', 'e']
if 1 then 1 else 0
if True then (head (True, False)) else False
if True then True else (head (False, True))
if True then ('t','r', 'u', 'e') else ['t','r', 'u', 'e']

------------------------- infix operation -----------------------
--------------------------- correct -------------------------

(head [1,2])+3
3+(head [1,2])
1+2

------------------------- infix operation -----------------------
--------------------------- wrong -------------------------

(head (1,2))+3
3+(head (1,2))
1+'a'

------------------------- function operation -----------------------
--------------------------- correct -------------------------

(head [1,2])+3
(head [(+), (-), (*)]) 1 2


------------------------- function operation -----------------------
--------------------------- wrong -------------------------

(head (1,2))+3
(head ((+), (-), (*))) 1 2

---------------------------  Uminus -----------------------
--------------------------- correct -------------------------

-1

---------------------------  Uminus -----------------------
---------------------------  wrong -------------------------

-[1]

--------------------------- leftSection -----------------------
---------------------------  correct -------------------------
 
map ((head [10])-) [1,2]
map ("string"++) ["lit"]

--------------------------- leftSection -----------------------
---------------------------   wrong  -------------------------
 
map ((head 10)-) [1,2]
map ('s'++) ["lit"]

--------------------------- List -----------------------
-------------------------- correct -------------------------
 
[(head [1,2]), 2]
[1,(head [2,3]), 3]
[(head [(+),(*)]), (-)]

--------------------------- List -----------------------
-------------------------- wrong -------------------------
 
[(head (1,2)), 2]
[1,(head (2,3)), 3]
[(head [(+),(*)]), (++)]

--------------------------- tuple -----------------------
-------------------------- correct -------------------------
 
((head [1]), 2)
(1,(head [2]))
(1,(head [2]),3,4,5)

-------------------------- tuple -----------------------
-------------------------- wrong -------------------------
 
((head 1), 2)
(1,(head 2))
(1,(head 2),3,4,5)

-------------------------- arithSeq-----------------------
--------------------------- correct -------------------------

[(head [1])..10]
[1,(head [3])..10]
[1,3..(head [10])]

-------------------------- arithSeq-----------------------
--------------------------- wrong -------------------------

[(head 1)..10]
['a'..10]
[1,(head 3)..10]
[1,'a'..10]
[1,2..(head 10)]
[1,3..'a']

-- Following are several invalid list expressions.
-- they should return errors ... from the command line parser.
2:[True]
True:[1]


-- Following are several invalid expressions.
-- they should return errors ... from the command line parser.
fst ()
fst (1)
fst (1,2,3)
snd ()
snd (1)
snd (1,2,3)