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env set+inner

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This commit is contained in:
Fabian 2021-03-26 17:29:52 +01:00 committed by Joel Martin
parent 64af767e72
commit b8728f28ea
2 changed files with 26 additions and 18 deletions
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16
impls/sml/env.sml
View File

@ -1,5 +1,13 @@
datatype mal_env = ENV of (string * mal_type) list
type mal_defs = (string * mal_type) list
fun lookup (ENV fs) s =
fs |> List.find (eq s o #1)
|> Option.map #2
datatype mal_env = ENV of mal_defs
| INNER of (mal_defs * mal_env)
fun get (d:mal_defs) s =
d |> List.find (eq s o #1) |> Option.map #2
fun set s v (d:mal_defs) =
(s, v) :: (d |> List.filter (not o eq s o #1))
fun lookup (INNER (d, out)) s = (case get d s of NONE => lookup out s | x => x)
| lookup (ENV d) s = get d s

28
impls/sml/step3_env.sml
View File

@ -40,20 +40,20 @@ fun malMinus (INT b, INT a) = INT (a - b)
fun malDiv (INT b, INT a) = INT (a div b)
| malDiv _ = raise NotApplicable "can only divide integers"
val initEnv = ENV [
("+", FN (foldl malPlus (INT 0))),
("*", FN (foldl malTimes (INT 1))),
("-", FN (
fn [x] => malMinus (x, INT 0)
| x::xs => foldr malMinus x xs
| _ => raise NotApplicable "'-' requires at least one argument"
)),
("/", FN (
fn [x] => malDiv (x, INT 1)
| x::xs => foldr malDiv x xs
| _ => raise NotApplicable "'/' requires at least one argument"
))
]
val initEnv =
[] |> set "+"
(FN (foldl malPlus (INT 0)))
|> set "*"
(FN (foldl malTimes (INT 1)))
|> set "-"
(FN (fn [x] => malMinus (x, INT 0)
| x::xs => foldr malMinus x xs
| _ => raise NotApplicable "'-' requires arguments"))
|> set "/"
(FN (fn [x] => malDiv (x, INT 1)
| x::xs => foldr malDiv x xs
| _ => raise NotApplicable "'/' requires arguments"))
|> ENV
fun repl () =
let open TextIO