Curry: An Integrated Functional Logic Language

corresponding computed solution is
{x=0,y=0} | {x=2,y=4}
4.1.5 Floating Point Numbers
Similarly to integers, values like “3.14159” or “5.0e-4” are considered as constructors of type Float.
Since overloading is not included in the kernel version of Curry, the names of arithmetic functions
on floats are different from the corresponding functions on integers.
4.1.6 Lists
The type [t] denotes all lists whose elements are values of type t. The type of lists can be
considered as predefined by the declaration
data [a] = [] | a : [a]
where [] denotes the empty list and x:xs is the non-empty list consisting of the first element x
and the remaining list xs. Since it is common to denote lists with square brackets, the following
convenient notation is supported:
[e1,e2,...,en]
denotes the list e1:e2:· · ·:en:[] (which is equivalent to e1:(e2:(· · ·:(en:[])...)) since “:” is a
right-associative infix operator). Note that there is an overloading in the notation [t]: if t is a
type, [t] denotes the type of lists containing elements of type t, where [t] denotes a single element
list (with element t) if t is an expression. Since there is a strong distinction between occurrences
of types and expressions, this overloading can always be resolved.
For instance, the following predefined functions define the concatenation of two lists and the
application of a function to all elements in a list:
(++) :: [a] -> [a] -> [a]
[] ++ ys = ys
(x:xs) ++ ys = x : xs ++ ys
map :: (a -> b) -> [a] -> [b]
map f [] = []
map f (x:xs) = f x : map f xs
4.1.7 Characters
Values like ’a’ or ’0’ denote constants of type Char. There are two conversion functions between
characters and their corresponding ASCII values:
ord :: Char -> Int
chr :: Int -> Char
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