genmeblog / okasaki

Purely Functional Data Structures in Clojure

okasaki

Purely Functional Data Structures in Clojure

https://www.amazon.com/gp/product/0521663504

Assumptions

• every data structure in separate namespace
• common API as protocols, however all API functions are duplicated in data structure namespaces (to wrap lazy cases)
• every data structure has own type (eg. LeftistHeap)
• if necessary empty is implemented as another type (eg. EmptyLeftistHeap)
• Clojure interop:
  • ->seq and seq -> Clojure sequence
  • ->TYPE (eg. ->stack) to convert sequence to desired type
  • ->structure to export internal structure as map
  • Indexed (for destructuring) and Seqable (for seq coersion) interfaces are implemented
• no speed or memory optimizations, possible SO exceptions

Creating

Two ways:

• empty-TYPE (eg. empty-heap) singleton is created for every data structure. Use it and feed with data.
• ->TYPE (eg. ->heap) to convert Clojure sequence to a type

Lazy evaluation

This is probably done wrong. I'm using delay and force to implement $ operator.

Other attempts

• https://github.com/jmgimeno/okasaki-clojure
• https://github.com/leonardoborges/purely-functional-data-structures