hash.adoc

Hash! datatype

Table of Contents

• 1. Abstract
• 2. Creation
  • 2.1. Runtime creation
• 3. Accessing hash! elements
  • 3.1. Using path! notation
  • 3.2. Using find
  • 3.3. Using select
• 4. Data set operations
• 5. Comparisons
• 6. Testing values
• 7. Predefined words
  • 7.1. Functions
  • 7.2. Natives

1. Abstract

A hash! value provides a block-like interface with fast lookups.

The underlying hashing function is a custom implementation of the MurmurHash3 algorithm.

Hash! is a member of the following typesets: default!, series!, any-block!, any-list!

2. Creation

Hash values can be created at runtime by using a make constructor or a to conversion.

2.1. Runtime creation

>> list: make hash! [a 123 "hello" b c 789]
== make hash! [a 123 "hello" b c 789]

>> list: to hash! [a 123 "hello" b c 789]
== make hash! [a 123 "hello" b c 789]

3. Accessing hash! elements

3.1. Using path! notation

Getting a value, using c as a key.

>> list/c
== 789

Setting a value, using c as a key.

>> list/c: 42
== 42

>> list
== make hash! [a 123 "hello" b c 42]

3.2. Using find

>> find list 'b
== make hash! [b c 42]

3.3. Using select

>> dict: make hash! [a 123 b 456 c 789]
== make hash! [a 123 b 456 c 789]

>> select dict 'c
== 789

>> dict: make hash! [2 123 4 456 6 2 8 789]
== make hash! [2 123 4 456 6 2 8 789]

>> select/skip dict 2 2
== 123

4. Data set operations

The following data set operations are possible with hash values: difference, exclude, intersect, union, unique

>> dict1: make hash! [a 123 b 456 c 789]
== make hash! [a 123 b 456 c 789]

>> dict2: make hash! [2 123 4 456 6 2 8 789]
== make hash! [2 123 4 456 6 2 8 789]

>> difference dict1 dict2
== make hash! [a b c 2 4 6 8]

>> exclude dict1 dict2
== make hash! [a b c]

>> intersect dict1 dict2
== make hash! [123 456 789]

>> union dict1 dict2
== make hash! [a 123 b 456 c 789 2 4 6 8]

>> unique dict2
== make hash! [2 123 4 456 6 8 789]

5. Comparisons

All comparators can be applied on hash!: =, ==, <>, >, <, >=, <=, =?. In addition, min, and max are also supported.

6. Testing values

Use hash? to check if a value is of the hash! datatype.

>> hash? dict1
== true

Use type? to return the datatype of a given value.

>> type? dict2
== hash!

7. Predefined words

7.1. Functions

average, hash?, path-thru, sum, to-hash

7.2. Natives

checksum, difference, exclude, extend, intersect, union, unique