An optimized in-memory key-value store, serving as a better performance replacement for default Scope implementation, designed for handling large data sets efficiently.

the speed gains will come at the expense of more memory usage


_ <- fat.extra.HashMap


Name Signature Brief
HashMap (capacity: Number = 97) Create a HashMap with a specified capacity

the default capacity of 97 is generally efficient for up to 10,000 items

Capacity Optimization

Ideally, you should keep at most about 100 items per 'bucket' in the hash table. In this context, 'capacity' refers to the number of buckets available for your data. Note that this implementation does not automatically adjust its size, so proper initial sizing is crucial. The following table can help determine the optimal capacity for storing n items:

n <   5000 => 53
n <  10000 => 97
n <  20000 => 193
n <  40000 => 389
n <  80000 => 769
n < 160000 => 1543
_          => 3079

using prime numbers can help reduce collisions

These values are based on empirical tests and should be adjusted according to your specific data needs and performance goals. Keep in mind that the relationship between capacity and performance is not entirely linear; as the number of items increases, the benefits of further increasing the capacity diminish.


Although the standard FatScript Scope exhibits slower performance for insertions and is particularly slow for deletions (such as setting to null), it excel in data retrieval and updates, outperforming HashMap for small collections (under ~500 items). Therefore, the benefits of using HashMap are most noticeable in scenarios involving frequent inserts and deletions on large data sets.

Prototype members

Name Signature Brief
isEmpty (): Boolean Returns true if length is zero
nonEmpty (): Boolean Returns true if length is non-zero
size (): Number Returns hash table length
toText (): Text Returns 'HashMap/capacity' as text literal
set (key: Text, value: Any): Any Set a key-value pair in the HashMap
get (key: Text): Any Get the value associated with a key
keys (): List/Text Return a list of all keys in the HashMap


_ <- fat.extra.HashMap

hmap = HashMap()
hmap.set('key1', 'value1')

hmap.get('key1')  # yields 'value1'
hmap.keys         # yields [ 'key1' ]

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