diff options
Diffstat (limited to 'txr.1')
| -rw-r--r-- | txr.1 | 58 |
1 files changed, 58 insertions, 0 deletions
@@ -8876,6 +8876,29 @@ the equal function instead. In addition to storing key-value pairs, a hash table can have a piece of information associated with it, called the user data. +.SS Functions make-similar-hash and copy-hash + +.TP +Syntax: + + (make-similar-hash <hash>) + (copy-hash <hash>) + +.TP +Description: + +The make-similar-hash and copy-hash functions create a new hash object based on +the existing <hash> object. + +The make-similar-hash produces an empty hash table which inherits all of the +attributes of <hash>. It uses the same kind of key equality, the +same configuration of weak keys and values, and has the same user data (see +the set-hash-userdata function). + +The copy-hash function is like make-similar-hash, except that instead of +producing an empty hash table, it produces one which has all the same elements +as <hash>: it contains the same key and value objects. + .SS Function sethash .TP @@ -9062,6 +9085,41 @@ The <result-form> and <body-form>-s are in the scope of an implicit anonymous block, which means that it is possible to terminate the execution of dohash early using (return) or (return <value>). +.SS Functions hash-uni, hash-diff and hash-isec + +.TP +Syntax: + + (hash-uni <hash1> <hash2>) + (hash-diff <hash1> <hash2>) + (hash-isec <hash1> <hash2>) + +.TP +Description: + +These functions perform basic set operations on hash tables in a nondestructive +way, returning a new hash table without altering the inputs. The arguments +<hash1> and <hash2> must be compatible hash tables. This means that their keys +must use the same kind of equality. + +The resulting hash table inherits attributes from <hash1>, as if by the +make-similar-hash operation. If <hash1> has userdata, the resulting hash table +has the same userdata. If <hash1> has weak keys, the resulting table has weak +keys, and so forth. + +The hash-uni function performs a set union. The resulting hash contains all of the +keys from <hash1> and all of the keys from <hash2>, and their corresponding values. +If a key occurs both in <hash1> and <hash2>, then it occurs only once in the +resulting hash. The value for this common key is the one from <hash2>. + +The hash-diff function performs a set difference. First, a copy of <hash1> is +made as if by the copy-has function. Then from this copy, all keys which occur +in <hash2> are deleted. + +The hash-isec function performs a set intersection. The resulting hash contains +only those keys which occur both in <hash1> and <hash2>. The values selected +for these common keys are those from <hash1>. + .SH PARTIAL EVALUATION AND COMBINATORS .SS Operator op |