Name Rascal/Libraries/Prelude

Synopsis The Rascal standard prelude.

Details Boolean DateTime Exception IO List ListRelation Map Message Node ParseTree Relation Set String Type ValueIO

Description The Prelude library contains core functionality for handling all of Rascal's data-types.

For basic numeric functions, see the Math library.

Prelude provides the following:

• Boolean:
• arbBool: Return an arbitrary Boolean value.
• fromString: Convert the strings "true" or "false" to a bool.
• toInt: Convert a Boolean value to integer.
• toReal: Convert Boolean value to real.
• toString: Convert Boolean value to string.
• DateTime:
• createDate: Create a new date.
• createDateTime: Create a new datetime (with optional timezone offset).
• createDuration: Create a new duration representing the duration between the begin and end dates.
• createInterval: Given two datetime values, create an interval.
• createTime: Create a new time (with optional timezone offset).
• dateRangeByDay: Given an interval, return a list of days.
• daysDiff: Return the difference between two dates and/or datetimes in days.
• daysInInterval: Return the number of days in an interval, including the begin and end days.
• decrementDays: Decrement the days by a given amount or by 1.
• decrementHours: Decrement the hours by a given amount or by 1.
• decrementMilliseconds: Decrement the milliseconds by a given amount or by 1.
• decrementMinutes: Decrement the minutes by a given amount or by 1.
• decrementMonths: Decrement the months by a given amount or by 1.
• decrementSeconds: Decrement the seconds by a given amount or by 1.
• decrementYears: Decrement the years by a given amount or by 1.
• Duration: A duration of time, measured in individual years, months, etc.
• incrementDays: Increment the days by given amount or by 1.
• incrementHours: Increment the hours by a given amount or by 1.`
• incrementMilliseconds: Increment the milliseconds by a given amount or by 1.
• incrementMinutes: Increment the minutes by a given amount or by 1.
• incrementMonths: Increment the months by a given amount or by 1.
• incrementSeconds: Increment the seconds by a given amount or by 1.
• incrementYears: Increment the years by given amount or by 1.
• interval: A closed interval on the time axis.
• joinDateAndTime: Create a new datetime by combining a date and a time.
• now: Get the current datetime.
• parseDate: Parse an input date given as a string using the given format string.
• parseDateInLocale: Parse an input date given as a string using a specific locale and format string.
• parseDateTime: Parse an input datetime given as a string using the given format string.
• parseDateTimeInLocale: Parse an input datetime given as a string using a specific locale and format string.
• parseTime: Parse an input time given as a string using the given format string.
• parseTimeInLocale: Parse an input time given as a string using a specific locale and format string.
• printDate: Print an input date using the given format string.
• printDateInLocale: Print an input date using a specific locale and format string.
• printDateTime: Print an input datetime using the given format string.
• printDateTimeInLocale: Print an input datetime using a specific locale and format string.
• printTime: Print an input time using the given format string.
• printTimeInLocale: Print an input time using a specific locale and format string.
• splitDateTime: Split an existing datetime into a tuple with the date and the time.
• Exception:
• RuntimeException: The Exception datatype used in all Rascal exceptions.
• IO:
• appendToFile: Append a value to a file.
• appendToFileEnc: Append a value to a file.
• bprintln: Print a value and return true.
• canEncode: Returns whether this charset can be used for encoding (use with writeFile)
• charsets: Returns all available character sets
• exists: Check whether a given location exists.
• find: Find a named file in a list of locations.
• iprint: Print an indented representation of a value.
• iprintExp: Print an indented representation of a value and returns the value as result.
• iprintln: Print a indented representation of a value and add a newline at the end.
• iprintlnExp: Print an indented representation of a value followed by a newline and returns the value as result.
• iprintToFile: Print an indented representation of a value to the specified location.
• isDirectory: Check whether a given location is a directory.
• isFile: Check whether a given location is actually a file (and not a directory).
• lastModified: Last modification date of a location.
• listEntries: List the entries in a directory.
• md5HashFile: Read the contents of a location and return its MD5 hash.
• mkDirectory: Create a new directory.
• print: Print a value without subsequent newline.
• printExp: Print a value and return it as result.
• println: Print a value to the output stream and add a newline.
• printlnExp: Print a value followed by a newline and return it as result.
• readFile: Read the contents of a location and return it as string value.
• readFileBytes: Read the contents of a file and return it as a list of bytes.
• readFileEnc: Read the contents of a location and return it as string value.
• readFileLines: Read the contents of a file location and return it as a list of strings.
• readFileLinesEnc: Read the contents of a file location and return it as a list of strings.
• rprint: Raw print of a value.
• rprintln: Raw print of a value followed by newline.
• touch: Changes the last modification date of a file.
• writeFile: Write values to a file.
• writeFileBytes: Write a list of bytes to a file.
• writeFileEnc: Write values to a file.
• List: Library functions for lists.
• delete: Delete an element from a list.
• distribution: Get the distribution of the elements of the list. That is how often does each element occur in the list?
• drop: Drop elements from the head of a list.
• dup: Remove multiple occurrences of elements in a list. The first occurrence remains.
• getOneFrom: Pick a random element from a list.
• head: Get the first element(s) from a list.
• headTail: Split a list in a head and a tail.
• index: A list of legal index values of a list.
• indexOf: Index of first occurrence of an element in a list.
• insertAt: Insert an element at a specific position in a list.
• intercalate: Join a list of values into a string separated by a separator.
• isEmpty: Test whether a list is empty.
• itoString: Convert a list to an indented string.
• last: Return the last element of a list, if any.
• lastIndexOf: Return index of last occurrence of elt in lst, or -1 if elt is not found.
• mapper: Apply a function to all list elements and return list of results.
• max: Determine the largest element in a list.
• merge: Merge the elements of two sorted lists into one list.
• min: Determine the smallest element in a list.
• mix: Mix the elements of two lists.
• permutations: Compute all permutations of a list.
• pop: Pop top element from list, return a tuple.
• prefix: Return all but the last element of a list.
• push: Push an element in front of a list.
• reducer: Apply a function to successive elements of list and combine the results (deprecated).
• reverse: Reverse a list.
• size: Determine the number of elements in a list.
• slice: Compute a sublist of a list.
• sort: Sort the elements of a list.
• split: Split a list into two halves.
• sum: Sum the elements of a list.
• tail: Get the tail element(s) from a list.
• take: Get number of elements from the head of a list.
• takeOneFrom: Remove an arbitrary element from a list, returns the element and the modified list.
• takeWhile: Take elements from the front of the list as long as a predicate is true.
• toMap: Convert a list of pairs to a map; first elements are associated with a set of second elements.
• toMapUnique: Convert a list of tuples to a map; result must be a map.
• top: Take the top element of a list.
• toRel: Convert a list to a relation.
• toSet: Convert a list to a set.
• toString: Convert a list to a string.
• unzip: Make a pair (triple) of lists from a list of pairs (triples).
• upTill: Returns the list 0,1..n-1.
• zip: Make a list of pairs from two (three) lists of the same length.
• ListRelation:
• carrier: Return the set of all elements in any tuple in a list relation.
• carrierR: A list relation restricted to certain element values in tuples.
• carrierX: A list relation excluding tuples that contain certain element values.
• complement: Complement of a list relation.
• domain: Domain of a list relation: a list consisting of the first element of each tuple.
• domainR: List relation restricted to certain domain elements.
• domainX: List relation excluding certain domain values.
• groupDomainByRange: Make sets of elements in the domain that relate to the same element in the range.
• groupRangeByDomain: Make sets of elements in the range that relate to the same element in the domain.
• ident: The identity list relation.
• index: Listes a binary list relation as a map
• invert: Invert the tuples in a list relation.
• range: The range (i.e., all but the first element of each tuple) of a list relation.
• rangeR: List relation restricted to certain range values.
• rangeX: List relation excluding certain range values.
• Map:
• delete: Delete a key from a map.
• domain: Determine the domain (set of keys) of a map.
• domainR: Map restricted to certain keys.
• domainX: Map with certain keys excluded.
• getOneFrom: Get a n arbitrary key from a map.
• invert: Invert the (key,value) pairs in a map.
• invertUnique: Invert the (key,value) pairs in a map.
• isEmpty: Test whether a map is empty.
• itoString: Convert a map to a indented string.
• mapper: Apply a function to all (key, value) pairs in a map.
• range: The range (set of values that correspond to its keys) of a map.
• rangeR: Map restricted to certain values in (key,values) pairs.
• rangeX: Map with certain values in (key,value) pairs excluded.
• size: Number of (key, value) pairs in a map.
• toList: Convert a map to a list of tuples.
• toRel: Convert a map to a relation.
• toString: Convert a map to a string.
• Message: A Message datatype that represents messages in the IDE.
• Message:
• Node:
• arity: Determine the number of children of a node.
• delAnnotation: Delete a specific annotation from a node.
• delAnnotations: Delete all annotations from a node.
• delAnnotationsRec: Delete recursively all annotations from all nodes in a value.
• getAnnotations: Retrieve the annotations of a node value as a map.
• getChildren: Get the children of a node.
• getKeywordParameters: Get the keyword parameters of a node.
• getName: Determine the name of a node.
• itoString: Convert a node to an indented string.
• makeNode: Create a node given its function name and arguments.
• setAnnotations: Add a map of annotations to a node value.
• toString: Convert a node to a string.
• ParseTree: Library functions for parse trees.
• associativity: Choice under associativity is flattened.
• Condition: constructors for declaring preconditions and postconditions on symbols
• doc: Annotate a parse tree node with a documentation string.
• docs: Annotate a parse tree node with documentation strings for several locations.
• implode: Implode a parse tree according to a given (ADT) type.
• isNonTerminalType:
• link: Annotate a parse tree node with the target of a reference.
• links: Annotate a parse tree node with multiple targets for a reference.
• loc: Annotate a parse tree node with a source location.
• message: Annotate a parse tree node with an (error) message.
• messages: Annotate a parse tree node with a list of (error) messages.
• parse: Parse input text (from a string or a location) and return a parse tree.
• priority: Nested priority is flattened.
• Production:
• saveParser: Save the current object parser to a file.
• Symbol:
• Tree: The Tree data type as produced by the parser.
• treeAt: Select the innermost Tree of a given type which is enclosed by a given location.
• TreeSearchResult: Tree search result type for treeAt.
• unparse: Yield the string of characters that form the leafs of the given parse tree.
• Relation:
• carrier: Return the set of all elements in any tuple in a relation.
• carrierR: A relation restricted to certain element values in tuples.
• carrierX: A relation excluding tuples that contain certain element values.
• complement: Complement of a relation.
• domain: Domain of a relation: a set consisting of the first element of each tuple.
• domainR: Relation restricted to certain domain elements.
• domainX: Relation excluding certain domain values.
• groupDomainByRange: Make sets of elements in the domain that relate to the same element in the range.
• groupRangeByDomain: Make sets of elements in the range that relate to the same element in the domain.
• ident: The identity relation.
• index: Indexes a binary relation as a map
• invert: Invert the tuples in a relation.
• range: The range (i.e., all but the first element of each tuple) of a relation.
• rangeR: Relation restricted to certain range values.
• rangeX: Relation excluding certain range values.
• Set: Library functions for sets.
• classify: Classify elements in a set.
• getOneFrom: Pick a random element from a set.
• group: Group elements in a set given an equivalence function.
• index: Map set elements to a fixed index.
• isEmpty: Test whether a set is empty.
• itoString: Convert a set to an indented string.
• mapper: Apply a function to all set elements and return set of results.
• max: Determine the largest element of a set.
• min: Smallest element of a set.
• power: Determine the powerset of a set.
• power1: The powerset (excluding the empty set) of a set value.
• reducer: Apply a function to successive elements of a set and combine the results (deprecated).
• size: Determine the number of elements in a set.
• sort: Sort the elements of a set. Sort the elements of a set: # Use the built-in ordering on values to compare list elements. # Give an additional lessThan function that will be used to compare elements. This function lessThan (<) function should implement a strict partial order, meaning: # that it is not reflexive, i.e. never a < a # is anti-symmetric, i.e. never a < b && b < a. # is transitive, i.e. if a < b and b < c then a < c.
• sum: Sum the elements of a set.
• takeOneFrom: Remove an arbitrary element from a set, returns the element and a set without that element.
• toList: Convert a set to a list.
• toMap: Convert a set of tuples to a map; each key is associated with a set of values.
• toMapUnique: Convert a set of tuples to a map (provided that there are no multiple keys).
• toString: Convert a set to a string.
• union: flatten a set of sets into a single set.
• String:
• center: Center a string in given space.
• charAt: Return character in a string by its index position.
• chars: Return characters of a string.
• contains: Check that a string contains another string.
• endsWith: Check whether a string ends with a given substring.
• escape: Replace single characters in a string.
• findAll: Find all occurrences of a string in another string.
• findFirst: Find the first occurrence of a string in another string.
• findLast: Find the last occurrence of a string in another string.
• isEmpty: Check whether a string is empty.
• isValidCharacter: Check that a given integer value is a valid Unicode code point.
• left: Left alignment of string in given space.
• replaceAll: Replace all occurrences of a string in another string.
• replaceFirst: Replace the first occurrence of a string in another string.
• replaceLast: Replace the last occurrence of a string in another string.
• reverse: Return a string with all characters in reverse order.
• rexpMatch: Determine if a string matches the given (Java-syntax) regular expression.
• right: Right align s in string of length n using space.
• size: Determine length of a string value.
• split: Split a string into a list of strings based on a literal separator.
• squeeze: Squeeze repeated occurrences of characters.
• startsWith: Check whether a string starts with a given prefix.
• stringChar: Convert a character code into a string.
• stringChars: Convert a list of character codes into a string.
• substring: Extract a substring from a string value.
• toInt: Convert a string value to integer.
• toLocation: Convert a string value to a (source code) location.
• toLowerCase: Convert the characters in a string value to lower case.
• toReal: Convert a string value to real.
• toUpperCase: Convert the characters in a string value to upper case.
• trim: Returns string with leading and trailing whitespace removed.
• wrap: word wrap a string to fit in a certain width.
• Type: This is a module that reflects Rascal's type system, implemented in Rascal itself.
• Attr: Attributes register additional semantics annotations of a definition.
• choice: Choice between alternative productions.
• comparable: Check if two types are comparable, i.e., have a common supertype.
• eq: structural equality between values.
• equivalent: Check if two types are equivalent.
• Exception:
• glb: The greatest lower bound (glb) between two types.
• isADTType: Determine if the given type is an Abstract Data Type (ADT).
• isAliasType: Determine if the given type is an alias.
• isBagType: Determine if the given type is a bag (bags are not yet implemented).
• isBoolType: Determine if the given type is a bool.
• isConstructorType: Determine if the given type is a constructor.
• isDateTimeType: Determine if the given type is a datetime.
• isFunctionType: Determine if the given type is a function.
• isIntType: Determine if the given type is an int.
• isListRelType: Determine if the given type is a list relation.
• isListType: Determine if the given type is a list.
• isLocType: Determine if the given type is a loc.
• isMapType: Determine if the given type is a map.
• isNodeType: Determine if the given type is a node.
• isNumType: Determine if the given type is a num.
• isRatType: Determine if the given type is a rational.
• isRealType: Determine if the given type is a real.
• isReifiedType: Determine if the given type is a reified type.
• isRelType: Determine if the given type is a relation.
• isSetType: Determine if the given type is a set.
• isStrType: Determine if the given type is a string.
• isTupleType: Determine if the given type is a tuple.
• isTypeVar: Determine if the given type is an type variable (parameter).
• isValueType: Determine if the given type is a value.
• isVoidType: Determine if the given type is a void.
• lub: The least-upperbound (lub) between two types.
• make: instantiate an ADT constructor of a given type with the given children
• Production: A production in a grammar or constructor in a data type.
• subtype:
• Symbol: A Symbol represents a Rascal Type.
• typeOf: returns the dynamic type of a value as a reified type
• var-func:
• ValueIO: Library functions for reading and writing values in textual and binary format.
• getFileLength:
• readBinaryValueFile:
• readTextValueFile:
• readTextValueFileWithEmbeddedTypes: If you have written a file containing reified types, then you can use this function to read them back.
• readTextValueString:
• readValueFile:
• writeBinaryValueFile:
• writeTextValueFile:

Benefits This library makes it possible to import all core Rascal functionality with a single import.

Pitfalls

• The prelude may contain more functionality than you need; this leads to an unnecessary longer import and pollution of your name space.
• The precise contents of the prelude are under discussion.
• In the future, Rascal may automatically load the prelude.

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