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Minor cleanup.

This commit is contained in:
Simon Forman 2022-09-24 14:54:07 -07:00
parent d99d9ee8aa
commit 10cdba844b
1 changed files with 30 additions and 5 deletions
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35
implementations/Ocaml/helloworld/bin/main.ml
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@ -15,26 +15,47 @@ let j_loop = JoySymbol "loop"
let zero = JoyInt 0
let dummy = JoyList [ joy_true; joy_false; j_loop; zero ]
let joy_nil = JoyList []
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https://stackoverflow.com/questions/13708701/how-to-implement-a-dictionary-as-a-function-in-ocaml
Note that when you call dict_add you omit the lookup parameter!
It becomes the input parameter to a curried function (closure)
that performs the key lookup at a later time when you call it,
> Remember that our definition of a dictionary here is function
> from key to values so this closure is a dictionary.
Just to really spell it out, the call:
dict_add dictionary key value
returns a function of signature:
string -> joy_list
That either return its own value (if the string arg equals its stored key)
or delegates to the (stored) dictionary function (itself string -> joy_list).
This is really cute, but a little too magical for my taste. Is this how you FP?
*)
exception UnknownWordError of string
let empty_dict (key : string) : joy_list = raise (UnknownWordError key)
let dict_add dictionary key value key' =
if key = key' then value else dictionary key'
let dict_add dictionary key value lookup =
if key = lookup then value else dictionary lookup
type joy_dict = string -> joy_list
let d = dict_add empty_dict "foo" []
(*
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@ -237,11 +258,15 @@ let rec joy : joy_list -> joy_list -> joy_dict -> joy_list * joy_dict =
joy s e d
| _ -> joy (head :: stack) tail dictionary)
(* Of course this could be a fold over a list of strings or something... *)
let d0 = dict_add empty_dict "++" (text_to_expression "1 +")
let d = dict_add d0 "sqr" (text_to_expression "dup mul")
(*
let expr = text_to_expression "1 2 + 3 4 + 5 6 + 7 8 + 9 10 + 11 + + + + + - "
let expr = text_to_expression "1 2 3 4 clear 5"
*)
let expr = text_to_expression "clear [23] [18] concat"
let expr = text_to_expression "clear [23] [18] concat 32 ++"
let s = text_to_expression "23 [18 99] "
let stack, _ = joy s expr d
let () = print_endline (expression_to_string stack)