fae58e140d
The old 'HashTable' type is now the union of the other 3 hash types. - all operations that used to work on 'HashTable's still work, but some now have more specific outputs - `#hash` literals have type `ImmutableHash` - `immutable?` and `hash-weak?` are filters - `Mutable-` and `Weak-` hashes have corresponding `Top` types, `HashTableTop` is now a union - the contact for `(U (Immutable-Hash K1 V1) (Mutable-Hash K2 V2))` is ONE `hash/c` Minor notes: - renamed internal identifiers containing 'Hashtable' to all use 'HashTable' - add Racket guide/reference 'secref' functions
17 lines
273 B
Racket
17 lines
273 B
Racket
#lang typed/scheme
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(: table (Immutable-HashTable Integer (-> Integer)))
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(define table
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(make-immutable-hash null))
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(: lookup (Integer -> Integer))
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(define (lookup n)
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(: thunk (-> Integer))
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(define thunk
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(hash-ref table n (lambda () n)))
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(thunk))
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(lookup 1)
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