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Here's a more or less equivalent implementation in Common Lisp, using alist-hash-table from alexandria: (defun csv-to-maps (csv) (loop for row in (re

Here's a more or less equivalent implementation in Common Lisp, using alist-hash-table from alexandria: (defun csv-to-maps (csv) (loop for row in (rest csv) collecting (alist-hash-table (mapcar #'cons (first csv) row) :test #'equal))) For CSVs with only a few columns (maybe less than 10?), I'd probably go with alists instead of a hash table to save memory, and it'd look like this, using curry from Alexandria: (defun csv-to-alists (csv) (map 'list (curry #'mapcar #'cons (first csv)) (rest csv)))

didibus 6y ago
If you read Rich's paper, there's a section where it says: > maps were built behind several abstractions. Thus, maps can start with a representation optimized for small maps and switch to a representation optimized for large collections if and when they ‘grow’ beyond a certain size. Which is pretty cool, because basically the Clojure version of your code abstracts over alist-hash-table and alist, and the most optimal type of concrete map will automatically be created based on the size of the map you are asking to create.
- jlarocco 6y ago
  There's actually an implementation of the same HAMT data structure that Clojure uses available in QuickLisp and on GitHub: https://github.com/danshapero/cl-hamt/ https://github.com/danshapero/cl-hamt/ Technically, since the hash-table implementation isn't specified in the CL standard an implementation could use a HAMT for the built-in hash tables, but I don't think any do.
  - didibus 6y ago
    The construction of a Map is abstract in Clojure. The concrete type of Map you get is not something you specify. This isn't related to the HAMT per say. So what I mean is Clojure will use an array backed map when you ask it to construct a small map, and it will give you a HAMT backed map when the map is large. This is true as well as you add elements to a map, Clojure might automatically promote the map from an array map to a HAMT as its size grows.

didibus 6y ago

If you read Rich's paper, there's a section where it says: > maps were built behind several abstractions. Thus, maps can start with a representation optimized for small maps and switch to a representation optimized for large collections if and when they ‘grow’ beyond a certain size. Which is pretty cool, because basically the Clojure version of your code abstracts over alist-hash-table and alist, and the most optimal type of concrete map will automatically be created based on the size of the map you are asking to create.

jlarocco 6y ago
There's actually an implementation of the same HAMT data structure that Clojure uses available in QuickLisp and on GitHub: https://github.com/danshapero/cl-hamt/ https://github.com/danshapero/cl-hamt/ Technically, since the hash-table implementation isn't specified in the CL standard an implementation could use a HAMT for the built-in hash tables, but I don't think any do.
- didibus 6y ago
  The construction of a Map is abstract in Clojure. The concrete type of Map you get is not something you specify. This isn't related to the HAMT per say. So what I mean is Clojure will use an array backed map when you ask it to construct a small map, and it will give you a HAMT backed map when the map is large. This is true as well as you add elements to a map, Clojure might automatically promote the map from an array map to a HAMT as its size grows.