GNU Info

(slib.info)Hash Tables

---

Next: Hashing Prev: Dynamic Data Type Up: Data Structures

---

Enter node , (file) or (file)node

Hash Tables
-----------

  `(require 'hash-table)'

 - Function: predicate->hash pred
     Returns a hash function (like `hashq', `hashv', or `hash')
     corresponding to the equality predicate PRED.  PRED should be
     `eq?', `eqv?', `equal?', `=', `char=?', `char-ci=?', `string=?', or
     `string-ci=?'.

  A hash table is a vector of association lists.

 - Function: make-hash-table k
     Returns a vector of K empty (association) lists.

  Hash table functions provide utilities for an associative database.
These functions take an equality predicate, PRED, as an argument.  PRED
should be `eq?', `eqv?', `equal?', `=', `char=?', `char-ci=?',
`string=?', or `string-ci=?'.

 - Function: predicate->hash-asso pred
     Returns a hash association function of 2 arguments, KEY and
     HASHTAB, corresponding to PRED.  The returned function returns a
     key-value pair whose key is PRED-equal to its first argument or
     `#f' if no key in HASHTAB is PRED-equal to the first argument.

 - Function: hash-inquirer pred
     Returns a procedure of 2 arguments, HASHTAB and KEY, which returns
     the value associated with KEY in HASHTAB or `#f' if KEY does not
     appear in HASHTAB.

 - Function: hash-associator pred
     Returns a procedure of 3 arguments, HASHTAB, KEY, and VALUE, which
     modifies HASHTAB so that KEY and VALUE associated.  Any previous
     value associated with KEY will be lost.

 - Function: hash-remover pred
     Returns a procedure of 2 arguments, HASHTAB and KEY, which
     modifies HASHTAB so that the association whose key is KEY is
     removed.

 - Function: hash-map proc hash-table
     Returns a new hash table formed by mapping PROC over the keys and
     values of HASH-TABLE.  PROC must be a function of 2 arguments
     which returns the new value part.

 - Function: hash-for-each proc hash-table
     Applies PROC to each pair of keys and values of HASH-TABLE.  PROC
     must be a function of 2 arguments.  The returned value is
     unspecified.