Plum is a programming language for writing functional, fast, reusable code.
Functional: Functions can't have side effects. Data is immutable and acyclic. Code is eagerly evaluated.
Fast: Types are known at compile time. Values have an efficient memory layout.
Reusable: You can write generic code. You can inspect types at compile time.
Type names are always uppercase. Type variables are lowercase. Use & to create structs and | to create enums.
Json =
| Int Int
Map (Map String Json)
Bool Bool
List t = & buffer: (Buffer t) len: Int
Function names are always lowercase or symbols. The signatures of functions have type annotations that allow you to figure out the return type without looking at the body.
+ a: Int b: Int = builtins.add a b
+ a: String b: String = builtins.concat a b
get list: (List t) index: Int -> t = ...
get map: (Map k v) key: k -> v = ...
parse json: Json target: Type -> target =
type_info target
% Int:
json
% Int int: int
else: crash "Expected int, found other stuff."
Struct fields:
json
% Map map:
...
else: crash ...