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Persistent HashMap for TypeScript
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TylorS/typed-hashmap
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Immutable HashMap for TypeScript
A fast and persistent (immutable) Hash Array Map Trie for TypeScript.
This is heavily based off ofhamt andwas mainly done by me for learning purposes, but it is likely very useful, and Iplan to use it as well.
Once main difference to the hamt library is that keys can be of any typeincluding objects or arrays much like ES2015Maps.Another notable change is there arenot prototype methods to allowfor ES2015 modules to be tree-shaken for smaller builds 🔥
There is a heavy emphasis on typing this library, and it's highly recommendedto be used with TypeScript to reap the full benefits of type guarantees.
There is more to be done but the bare minimum is definitely present.
npm install --save @typed/hashmap
All multi-parameter functions are curried!
####empty<K, V>(): HashMap<K, V>
Creates an empty HashMap that will accept typeK as keys andV as values.
import{empty}from'@typed/hashmap';constmap=empty<string,number>();
Creates a HashMap from an object.
import{fromObject}from'@typed/hashmap';constmap=fromObject<number>({a:1,b:2});
Creates a HashMap from an array of tuples.
import{fromArray}from'@typed/hashmap';constmap=fromArray<string,number>([['a',1],['b',2]]);
Creates a HashMap from an Iterable.
Warning: this method usingArray.from internally, and will require a polyfillif not in an environment that supports this feature.
import{fromIterable}from'@typed/hashmap';constmap=fromIterable(someIterable);
Returns a new HashMap containing thekey andvalue passed toset.This operation is immutable and will not alter the map passed to it.
import{set,get,empty}from'@typed/hashmap';constmap=empty<string,number>();consta=set('a',1,map);console.log(get('a',a))// 1
Attempts to find a value in a given HashMap. Returnsnull if none can be found.
import{set,get,empty}from'@typed/hashmap';constmap=empty<string,number>();consta=set('a',1,map);console.log(get('a',a))// 1
Returns true if a map contains a particular key and false if it does not.
import{empty,has,set}from'@typed/hashmap';consthasA=has('a');constmap=empty<string,number>();hasA(map)// falsehasA(set('a',1,map))// true
Returns the number of key value pairs a given map contains
import{size,empty,fromObject}from'@typed/hashmap';size(empty())// 0size(fromObject({a:1,b:2}))// 2
Returns a HashMap that no longer contains a value forkey.
import{remove,fromObject,has}from'@typed/hashmap';constmap=fromObject({a:1,b:2,c:3})consthasB=has('b')hasB(map)// truehasB(remove('b',map))// false
Guaranteeing no order creates an iterator of keys and values held withina given HashMap.
import{entries,fromObject}from'@typed/hashmap';constmap=fromObject({a:1,b:2,c:3})for(letentryofentries(map)){console.log(entry)// ['a', 1] ['b', 2] ['c' 3]}// manually using iteratorconstiterator=entries(map)console.log(iterator.next().value)// ['a', 1]console.log(iterator.next().value)// ['c', 3]console.log(iterator.next().value)// ['b', 2]console.log(iterator.next().value)// null
Guaranteeing no order creates an iterator of keys held withina given HashMap.
import{keys,fromArray}from'@typed/hashmap';constmap=fromArray([['a',1],['b',2],['c',3]])constiterator=keys(map)console.log(iterator.next().value)// 'a'console.log(iterator.next().value)// 'b'console.log(iterator.next().value)// 'c'console.log(iterator.next().value)// null
Guaranteeing no order creates an iterator of keys held withina given HashMap.
import{keys,fromArray}from'@typed/hashmap';constmap=fromArray([['a',1],['b',2],['c',3]])constiterator=keys(map)console.log(iterator.next().value)// 1console.log(iterator.next().value)// 2console.log(iterator.next().value)// 3console.log(iterator.next().value)// null
Fold over the values held in a HashMap, similar toArray.prototype.reduce.
import{reduce,fromIterable}from'@typed/hashmap';constiterable=newMap([[1,1],[2,2],[3,3]]);constmap=fromIterable(iterable);constsum=(x:number,y:number)=>x+y;console.log(reduce(sum,0,map))// 6
Perform side effects on each value contained in a HashMap, returning the originalHashMap.
import{forEach,fromObject}from'@typed/hashmap';constmap=fromObject({a:1,b:2,c:3})constmap2=forEach(x=>console.log(x),map)// 1, 2, 3map===map2// true
Creates a new HashMap of the same keys, but new values as the result of callingthe provided function on each value contained in the given HashMap, similar toArray.prototype.map.
import{map,forEach,fromObject}from'@typed/hashmap';consta=map(x=>x+1,fromObject({a:1,b:2,c:3}))forEach((value,key)=>console.log(value,key),a)// 'a' 2 , 'b' 3, 'c' 4
Creates a new HashMap containing only values that returntrue when the predicatefunction is called with a given value, similar toArray.prototype.filter.
import{filter,forEach,fromObject}from'@typed/hashmap';consta=filter(x=>x%2===0,fromObject({a:1,b:2,c:3}))forEach((value,key)=>console.log(value,key),a)// 'b' 2
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Persistent HashMap for TypeScript