cyclone/docs/api/srfi/69.md

SRFI 69 - Basic hash tables

The (srfi 69) library defines basic hash tables.

Hash tables are widely recognised as a fundamental data structure for a wide variety of applications. A hash table is a data structure that:

• provides a mapping from some set of keys to some set of values associated to those keys
• has no intrinsic order for the (key, value) associations it contains
• supports in-place modification as the primary means of setting the contents of a hash table
• provides key lookup and destructive update in amortised constant time, provided that a good hash function is used

See the SRFI document for more information.

• make-hash-table
• hash-table?
• alist->hash-table
• hash-table-equivalence-function
• hash-table-hash-function
• hash-table-ref
• hash-table-ref/default
• hash-table-set!
• hash-table-delete!
• hash-table-exists?
• hash-table-update!
• hash-table-update!/default
• hash-table-size
• hash-table-keys
• hash-table-values
• hash-table-walk
• hash-table-fold
• hash-table->alist
• hash-table-copy
• hash-table-merge!
• hash
• string-hash
• string-ci-hash
• hash-by-identity

#make-hash-table (make-hash-table) (make-hash-table equal?) (make-hash-table equal? hash) (make-hash-table equal? hash size) Create a new hash table. #hash-table? (hash-table? obj) Determine if the given object is a hash table. #alist->hash-table (alist->hash-table alist) (alist->hash-table alist equal?) (alist->hash-table alist equal? hash) Convert given association list to a hash table. #hash-table-equivalence-function (hash-table-equivalence-function hash-table) Returns the equivalence predicate used for keys of hash-table. #hash-table-hash-function (hash-table-hash-function hash-table) Returns the hash function used for keys of hash-table. #hash-table-ref (hash-table-ref hash-table key) (hash-table-ref hash-table key thunk) This procedure returns the value associated to key in hash-table. If no value is associated to key and thunk is given, it is called with no arguments and its value is returned. #hash-table-ref/default (hash-table-ref/default hash-table key default) Return the value associated to key in the hash table, or default if the key is not found. #hash-table-set! (hash-table-set! hash-table key value) Sets the value associated to key in the given hash table. #hash-table-delete! (hash-table-delete! hash-table key) Removes any value association for key in the given hash table. #hash-table-exists? (hash-table-exists? hash-table key) Determines if the given key exists in the hash table. #hash-table-update! (hash-table-update! hash-table key function) (hash-table-update! hash-table key function thunk) #hash-table-update!/default (hash-table-update!/default hash-table key function default) #hash-table-size (hash-table-size hash-table) Return the number of associations in the hash table. #hash-table-keys (hash-table-keys hash-table) Return a list of keys in the hash table. #hash-table-values (hash-table-values hash-table) Return a list of values in the hash table. #hash-table-walk (hash-table-walk hash-table proc) proc should be a function taking two arguments, a key and a value. This procedure calls proc for each association in hash-table, giving the key of the association as key and the value of the association as value. The results of proc are discarded. #hash-table-fold (hash-table-fold hash-table f init-value) This procedure calls f for every association in hash-table with three arguments: the key of the association key, the value of the association value, and an accumulated value, val. val is init-value for the first invocation of f, and for subsequent invocations of f, the return value of the previous invocation of f. The value final-value returned by hash-table-fold is the return value of the last invocation of f. #hash-table->alist (hash-table->alist hash-table) Return an association list using the keys and values from the hash table. #hash-table-copy (hash-table-copy hash-table) Return a new hash table with the same data as the original. #hash-table-merge! (hash-table-merge! hash-table1 hash-table2) Adds all mappings in hash-table2 into hash-table1 and returns the resulting hash table. #hash (hash object) (hash object bound) Return a hash value for object in the range 0 to bound. #string-hash (string-hash string) (string-hash string bound) Same as hash except the argument must be a string. #string-ci-hash (string-ci-hash string) (string-ci-hash string bound) Case insensitive version of string-hash. #hash-by-identity (hash-by-identity object) (hash-by-identity object bound) The same as hash, except that this function is only guaranteed to be acceptable for eq?.