The standard prelude of Curry (with type classes). All exported functions, data types, classes, and methods defined in this module are always available in any Curry program.
(.)
:: (a -> b) -> (c -> a) -> c -> b
Function composition. |
id
:: a -> a
Identity function. |
const
:: a -> b -> a
Constant function. |
curry
:: ((a,b) -> c) -> a -> b -> c
Converts an uncurried function to a curried function. |
uncurry
:: (a -> b -> c) -> (a,b) -> c
Converts an curried function to a function on pairs. |
flip
:: (a -> b -> c) -> b -> a -> c
(flip f) is identical to f but with the order of arguments reversed. |
until
:: (a -> Bool) -> (a -> a) -> a -> a
Repeats application of a function until a predicate holds. |
seq
:: a -> b -> b
Evaluates the first argument to head normal form (which could also be a free variable) and returns the second argument. |
ensureNotFree
:: a -> a
Evaluates the argument to head normal form and returns it. |
ensureSpine
:: [a] -> [a]
Evaluates the argument to spine form and returns it. |
($)
:: (a -> b) -> a -> b
Right-associative application. |
($!)
:: (a -> b) -> a -> b
Right-associative application with strict evaluation of its argument to head normal form. |
($!!)
:: (a -> b) -> a -> b
Right-associative application with strict evaluation of its argument to normal form. |
($#)
:: (a -> b) -> a -> b
Right-associative application with strict evaluation of its argument to a non-variable term. |
($##)
:: (a -> b) -> a -> b
Right-associative application with strict evaluation of its argument to ground normal form. |
error
:: String -> a
Aborts the execution with an error message. |
failed
:: a
A non-reducible polymorphic function. |
(&&)
:: Bool -> Bool -> Bool
Sequential conjunction on Booleans. |
(||)
:: Bool -> Bool -> Bool
Sequential disjunction on Booleans. |
not
:: Bool -> Bool
Negation on Booleans. |
otherwise
:: Bool
Useful name for the last condition in a sequence of conditional equations. |
if_then_else
:: Bool -> a -> a -> a
The standard conditional. |
solve
:: Bool -> Bool
Enforce a Boolean condition to be true. |
(&>)
:: Bool -> a -> a
Conditional expression. |
(=:=)
:: a -> a -> Bool
The equational constraint. |
(&)
:: Bool -> Bool -> Bool
Concurrent conjunction. |
fst
:: (a,b) -> a
Selects the first component of a pair. |
snd
:: (a,b) -> b
Selects the second component of a pair. |
head
:: [a] -> a
Computes the first element of a list. |
tail
:: [a] -> [a]
Computes the remaining elements of a list. |
null
:: [a] -> Bool
Is a list empty? |
(++)
:: [a] -> [a] -> [a]
Concatenates two lists. |
length
:: [a] -> Int
Computes the length of a list. |
(!!)
:: [a] -> Int -> a
List index (subscript) operator, head has index 0. |
map
:: (a -> b) -> [a] -> [b]
Map a function on all elements of a list. |
foldl
:: (a -> b -> a) -> a -> [b] -> a
Accumulates all list elements by applying a binary operator from left to right. |
foldl1
:: (a -> a -> a) -> [a] -> a
Accumulates a non-empty list from left to right. |
foldr
:: (a -> b -> b) -> b -> [a] -> b
Accumulates all list elements by applying a binary operator from right to left. |
foldr1
:: (a -> a -> a) -> [a] -> a
Accumulates a non-empty list from right to left: |
filter
:: (a -> Bool) -> [a] -> [a]
Filters all elements satisfying a given predicate in a list. |
zip
:: [a] -> [b] -> [(a,b)]
Joins two lists into one list of pairs. |
zip3
:: [a] -> [b] -> [c] -> [(a,b,c)]
Joins three lists into one list of triples. |
zipWith
:: (a -> b -> c) -> [a] -> [b] -> [c]
Joins two lists into one list by applying a combination function to corresponding pairs of elements. |
zipWith3
:: (a -> b -> c -> d) -> [a] -> [b] -> [c] -> [d]
Joins three lists into one list by applying a combination function to corresponding triples of elements. |
unzip
:: [(a,b)] -> ([a],[b])
Transforms a list of pairs into a pair of lists. |
unzip3
:: [(a,b,c)] -> ([a],[b],[c])
Transforms a list of triples into a triple of lists. |
concat
:: [[a]] -> [a]
Concatenates a list of lists into one list. |
concatMap
:: (a -> [b]) -> [a] -> [b]
Maps a function from elements to lists and merges the result into one list. |
iterate
:: (a -> a) -> a -> [a]
Infinite list of repeated applications of a function f to an element x. |
repeat
:: a -> [a]
Infinite list where all elements have the same value. |
replicate
:: Int -> a -> [a]
List of length n where all elements have the same value. |
take
:: Int -> [a] -> [a]
Returns prefix of length n. |
drop
:: Int -> [a] -> [a]
Returns suffix without first n elements. |
splitAt
:: Int -> [a] -> ([a],[a])
(splitAt n xs) is equivalent to (take n xs, drop n xs) |
takeWhile
:: (a -> Bool) -> [a] -> [a]
Returns longest prefix with elements satisfying a predicate. |
dropWhile
:: (a -> Bool) -> [a] -> [a]
Returns suffix without takeWhile prefix. |
span
:: (a -> Bool) -> [a] -> ([a],[a])
(span p xs) is equivalent to (takeWhile p xs, dropWhile p xs) |
break
:: (a -> Bool) -> [a] -> ([a],[a])
(break p xs) is equivalent to (takeWhile (not.p) xs, dropWhile (not.p) xs). |
lines
:: String -> [String]
Breaks a string into a list of lines where a line is terminated at a newline character. |
unlines
:: [String] -> String
Concatenates a list of strings with terminating newlines. |
words
:: String -> [String]
Breaks a string into a list of words where the words are delimited by white spaces. |
unwords
:: [String] -> String
Concatenates a list of strings with a blank between two strings. |
reverse
:: [a] -> [a]
Reverses the order of all elements in a list. |
and
:: [Bool] -> Bool
Computes the conjunction of a Boolean list. |
or
:: [Bool] -> Bool
Computes the disjunction of a Boolean list. |
any
:: (a -> Bool) -> [a] -> Bool
Is there an element in a list satisfying a given predicate? |
all
:: (a -> Bool) -> [a] -> Bool
Is a given predicate satisfied by all elements in a list? |
elem
:: Eq a => a -> [a] -> Bool
Element of a list? |
notElem
:: Eq a => a -> [a] -> Bool
Not element of a list? |
lookup
:: Eq a => a -> [(a,b)] -> Maybe b
Looks up a key in an association list. |
enumFrom_
:: Int -> [Int]
Generates an infinite sequence of ascending integers. |
enumFromThen_
:: Int -> Int -> [Int]
Generates an infinite sequence of integers with a particular in/decrement. |
enumFromTo_
:: Int -> Int -> [Int]
Generates a sequence of ascending integers. |
enumFromThenTo_
:: Int -> Int -> Int -> [Int]
Generates a sequence of integers with a particular in/decrement. |
ord
:: Char -> Int
Converts a character into its ASCII value. |
chr
:: Int -> Char
Converts a Unicode value into a character. |
negate_
:: Int -> Int
Unary minus. |
negateFloat
:: Float -> Float
Unary minus on Floats. |
success
:: Bool
The always satisfiable constraint. |
maybe
:: a -> (b -> a) -> Maybe b -> a
|
either
:: (a -> b) -> (c -> b) -> Either a c -> b
|
done
:: IO ()
The empty IO action that returns nothing. |
putChar
:: Char -> IO ()
An action that puts its character argument on standard output. |
getChar
:: IO Char
An action that reads a character from standard output and returns it. |
readFile
:: String -> IO String
An action that (lazily) reads a file and returns its contents. |
writeFile
:: String -> String -> IO ()
An action that writes a file. |
appendFile
:: String -> String -> IO ()
An action that appends a string to a file. |
putStr
:: String -> IO ()
Action to print a string on stdout. |
putStrLn
:: String -> IO ()
Action to print a string with a newline on stdout. |
getLine
:: IO String
Action to read a line from stdin. |
userError
:: String -> IOError
A user error value is created by providing a description of the error situation as a string. |
ioError
:: IOError -> IO a
Raises an I/O exception with a given error value. |
showError
:: IOError -> String
Shows an error values as a string. |
catch
:: IO a -> (IOError -> IO a) -> IO a
Catches a possible error or failure during the execution of an I/O action. |
print
:: Show a => a -> IO ()
Converts a term into a string and prints it. |
doSolve
:: Bool -> IO ()
Solves a constraint as an I/O action. |
sequenceIO
:: [IO a] -> IO [a]
Executes a sequence of I/O actions and collects all results in a list. |
sequenceIO_
:: [IO a] -> IO ()
Executes a sequence of I/O actions and ignores the results. |
mapIO
:: (a -> IO b) -> [a] -> IO [b]
Maps an I/O action function on a list of elements. |
mapIO_
:: (a -> IO b) -> [a] -> IO ()
Maps an I/O action function on a list of elements. |
foldIO
:: (a -> b -> IO a) -> a -> [b] -> IO a
Folds a list of elements using an binary I/O action and a value for the empty list. |
liftIO
:: (a -> b) -> IO a -> IO b
Apply a pure function to the result of an I/O action. |
forIO
:: [a] -> (a -> IO b) -> IO [b]
Like mapIO , but with flipped arguments.
|
forIO_
:: [a] -> (a -> IO b) -> IO ()
Like mapIO_ , but with flipped arguments.
|
unless
:: Bool -> IO () -> IO ()
Performs an IO
action unless the condition is met.
|
when
:: Bool -> IO () -> IO ()
Performs an IO
action when the condition is met.
|
(?)
:: a -> a -> a
Non-deterministic choice par excellence. |
anyOf
:: [a] -> a
|
unknown
:: a
Evaluates to a fresh free variable. |
PEVAL
:: a -> a
Identity function used by the partial evaluator to mark expressions to be partially evaluated. |
normalForm
:: a -> a
Evaluates the argument to normal form and returns it. |
groundNormalForm
:: a -> a
Evaluates the argument to ground normal form and returns it. |
apply
:: (a -> b) -> a -> b
|
cond
:: Bool -> a -> a
|
letrec
:: a -> a -> Bool
This operation is internally used by PAKCS to implement recursive let s by using cyclic term structures.
|
(=:<=)
:: a -> a -> Bool
Non-strict equational constraint. |
(=:<<=)
:: a -> a -> Bool
Non-strict equational constraint for linear functional patterns. |
shows
:: Show a => a -> String -> String
|
showChar
:: Char -> String -> String
|
showString
:: String -> String -> String
|
showParen
:: Bool -> (String -> String) -> String -> String
|
reads
:: Read a => String -> [(a,String)]
|
readParen
:: Bool -> (String -> [(a,String)]) -> String -> [(a,String)]
|
read
:: Read a => String -> a
|
lex
:: String -> [(String,String)]
|
boundedEnumFrom
:: (Bounded a, Enum a) => a -> [a]
|
boundedEnumFromThen
:: (Bounded a, Enum a) => a -> a -> [a]
|
asTypeOf
:: a -> a -> a
|
sequence
:: Monad a => [a b] -> a [b]
Evaluates a sequence of monadic actions and collects all results in a list. |
sequence_
:: Monad a => [a b] -> a ()
Evaluates a sequence of monadic actions and ignores the results. |
mapM
:: Monad a => (b -> a c) -> [b] -> a [c]
Maps a monadic action function on a list of elements. |
mapM_
:: Monad a => (b -> a c) -> [b] -> a ()
Maps a monadic action function on a list of elements. |
foldM
:: Monad a => (b -> c -> a b) -> b -> [c] -> a b
Folds a list of elements using a binary monadic action and a value for the empty list. |
liftM
:: Monad a => (b -> c) -> a b -> a c
Apply a pure function to the result of a monadic action. |
liftM2
:: Monad a => (b -> c -> d) -> a b -> a c -> a d
Apply a pure binary function to the result of two monadic actions. |
forM
:: Monad a => [b] -> (b -> a c) -> a [c]
Like mapM , but with flipped arguments.
|
forM_
:: Monad a => [b] -> (b -> a c) -> a ()
Like mapM_ , but with flipped arguments.
|
unlessM
:: Monad a => Bool -> a () -> a ()
Performs a monadic action unless the condition is met. |
whenM
:: Monad a => Bool -> a () -> a ()
Performs a monadic action when the condition is met. |
Constructors:
Constructors:
Constructors:
Type synonym: String = [Char]
Constructors:
False
:: Bool
True
:: Bool
Ordering type. Useful as a result of comparison functions.
Constructors:
LT
:: Ordering
EQ
:: Ordering
GT
:: Ordering
Type synonym: Success = Bool
Constructors:
Nothing
:: Maybe a
Just
:: a -> Maybe a
Constructors:
Left
:: a -> Either a b
Right
:: b -> Either a b
Constructors:
The (abstract) type of error values.
Currently, it distinguishes between general IO errors,
user-generated errors (see userError
), failures and non-determinism
errors during IO computations. These errors can be caught by catch
and shown by showError
.
Each error contains a string shortly explaining the error.
This type might be extended in the future to distinguish
further error situations.
Constructors:
IOError
:: String -> IOError
UserError
:: String -> IOError
FailError
:: String -> IOError
NondetError
:: String -> IOError
Identity type synonym used to mark deterministic operations.
Type synonym: DET a = a
Type synonym: ShowS = String -> String
Type synonym: ReadS a = String -> [(a,String)]
Function composition.
|
Identity function.
|
Constant function.
|
Converts an uncurried function to a curried function. |
Converts an curried function to a function on pairs. |
(flip f) is identical to f but with the order of arguments reversed. |
Repeats application of a function until a predicate holds. |
Evaluates the first argument to head normal form (which could also be a free variable) and returns the second argument.
|
Evaluates the argument to head normal form and returns it. Suspends until the result is bound to a non-variable term.
|
Evaluates the argument to spine form and returns it. Suspends until the result is bound to a non-variable spine. |
Right-associative application.
|
Right-associative application with strict evaluation of its argument to head normal form.
|
Right-associative application with strict evaluation of its argument to normal form.
|
Right-associative application with strict evaluation of its argument to a non-variable term.
|
Right-associative application with strict evaluation of its argument to ground normal form.
|
Aborts the execution with an error message. |
A non-reducible polymorphic function.
It is useful to express a failure in a search branch of the execution.
It could be defined by:
|
Sequential conjunction on Booleans.
|
Sequential disjunction on Booleans.
|
Negation on Booleans.
|
Useful name for the last condition in a sequence of conditional equations.
|
The standard conditional. It suspends if the condition is a free variable. |
Enforce a Boolean condition to be true.
The computation fails if the argument evaluates to
|
Conditional expression.
An expression like
|
The equational constraint.
|
Concurrent conjunction.
An expression like
|
Selects the first component of a pair.
|
Selects the second component of a pair.
|
Computes the first element of a list.
|
Computes the remaining elements of a list.
|
Is a list empty?
|
Concatenates two lists. Since it is flexible, it could be also used to split a list into two sublists etc.
|
Computes the length of a list. |
List index (subscript) operator, head has index 0.
|
Map a function on all elements of a list. |
Accumulates all list elements by applying a binary operator from left to right. Thus, foldl f z [x1,x2,...,xn] = (...((z `f` x1) `f` x2) ...) `f` xn |
Accumulates a non-empty list from left to right.
|
Accumulates all list elements by applying a binary operator from right to left. Thus, foldr f z [x1,x2,...,xn] = (x1 `f` (x2 `f` ... (xn `f` z)...)) |
Accumulates a non-empty list from right to left:
|
Filters all elements satisfying a given predicate in a list. |
Joins two lists into one list of pairs. If one input list is shorter than the other, the additional elements of the longer list are discarded.
|
Joins three lists into one list of triples. If one input list is shorter than the other, the additional elements of the longer lists are discarded.
|
Joins two lists into one list by applying a combination function to
corresponding pairs of elements. Thus |
Joins three lists into one list by applying a combination function to
corresponding triples of elements. Thus |
Transforms a list of pairs into a pair of lists.
|
Transforms a list of triples into a triple of lists.
|
Concatenates a list of lists into one list. |
Maps a function from elements to lists and merges the result into one list. |
Infinite list of repeated applications of a function f to an element x.
Thus, |
Infinite list where all elements have the same value.
Thus,
|
List of length n where all elements have the same value. |
Returns prefix of length n. |
Returns suffix without first n elements. |
(splitAt n xs) is equivalent to (take n xs, drop n xs) |
Returns longest prefix with elements satisfying a predicate. |
Returns suffix without takeWhile prefix. |
(span p xs) is equivalent to (takeWhile p xs, dropWhile p xs) |
(break p xs) is equivalent to (takeWhile (not.p) xs, dropWhile (not.p) xs). Thus, it breaks a list at the first occurrence of an element satisfying p. |
Breaks a string into a list of lines where a line is terminated at a newline character. The resulting lines do not contain newline characters. |
Concatenates a list of strings with terminating newlines. |
Breaks a string into a list of words where the words are delimited by white spaces. |
Concatenates a list of strings with a blank between two strings. |
Reverses the order of all elements in a list. |
Computes the conjunction of a Boolean list. |
Computes the disjunction of a Boolean list. |
Is there an element in a list satisfying a given predicate? |
Is a given predicate satisfied by all elements in a list? |
Element of a list?
|
Not element of a list?
|
Looks up a key in an association list. |
Generates an infinite sequence of ascending integers. |
Generates an infinite sequence of integers with a particular in/decrement. |
Generates a sequence of ascending integers. |
Generates a sequence of integers with a particular in/decrement. |
Converts a character into its ASCII value. |
Converts a Unicode value into a character. The conversion is total, i.e., for out-of-bound values, the smallest or largest character is generated. |
Unary minus. Usually written as "- e". |
Unary minus on Floats. Usually written as "-e". |
The always satisfiable constraint.
|
|
|
The empty IO action that returns nothing. |
An action that puts its character argument on standard output. |
An action that reads a character from standard output and returns it.
|
An action that (lazily) reads a file and returns its contents. |
An action that writes a file.
|
An action that appends a string to a file. It behaves like writeFile if the file does not exist.
|
Action to print a string on stdout. |
Action to print a string with a newline on stdout. |
Action to read a line from stdin. |
A user error value is created by providing a description of the error situation as a string.
|
Raises an I/O exception with a given error value. |
Shows an error values as a string.
|
Catches a possible error or failure during the execution of an
I/O action.
|
Converts a term into a string and prints it. |
Solves a constraint as an I/O action. Note: the constraint should be always solvable in a deterministic way |
Executes a sequence of I/O actions and collects all results in a list. |
Executes a sequence of I/O actions and ignores the results. |
Maps an I/O action function on a list of elements. The results of all I/O actions are collected in a list. |
Maps an I/O action function on a list of elements. The results of all I/O actions are ignored. |
Folds a list of elements using an binary I/O action and a value for the empty list. |
Apply a pure function to the result of an I/O action. |
Like This can be useful if the definition of the function is longer than those of the list, like in forIO [1..10] $ \n -> do ... |
Like This can be useful if the definition of the function is longer than those of the list, like in forIO_ [1..10] $ \n -> do ... |
Performs an |
Performs an |
Non-deterministic choice par excellence.
The value of
|
|
Evaluates to a fresh free variable.
|
Identity function used by the partial evaluator to mark expressions to be partially evaluated.
|
Evaluates the argument to normal form and returns it. |
Evaluates the argument to ground normal form and returns it. Suspends as long as the normal form of the argument is not ground. |
|
|
This operation is internally used by PAKCS to implement recursive
letrec ones (1:ones)
(where
|
Non-strict equational constraint. Used to implement functional patterns.
|
Non-strict equational constraint for linear functional patterns. Thus, it must be ensured that the first argument is always (after evalutation by narrowing) a linear pattern. Experimental.
|
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Evaluates a sequence of monadic actions and collects all results in a list. |
Evaluates a sequence of monadic actions and ignores the results. |
Maps a monadic action function on a list of elements. The results of all monadic actions are collected in a list. |
Maps a monadic action function on a list of elements. The results of all monadic actions are ignored. |
Folds a list of elements using a binary monadic action and a value for the empty list. |
Apply a pure function to the result of a monadic action. |
Apply a pure binary function to the result of two monadic actions. |
Like This can be useful if the definition of the function is longer than those of the list, like in forM [1..10] $ \n -> do ... |
Like This can be useful if the definition of the function is longer than those of the list, like in forM_ [1..10] $ \n -> do ... |
Performs a monadic action unless the condition is met. |
Performs a monadic action when the condition is met. |