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Diffstat (limited to 'README.md')
| -rw-r--r-- | README.md | 29 |
1 files changed, 15 insertions, 14 deletions
@@ -6,7 +6,7 @@ Puck is an experimental, memory safe, structurally typed, interface-first, imper It aims to be clean and succinct while performant: inspired by the syntax and metaprogramming of [Nim](https://nim-lang.org/), the error handling of [Swift](https://www.swift.org/), the performance and safety guarantees of [Rust](https://www.rust-lang.org/), the async/await and comptime of [Zig](https://ziglang.org/), and the module system of [OCaml](https://ocaml.org/). <details> -<summary><b>Example: Interfaces</b></summary> +<summary><b>Example: Type Classes</b></summary> ```nim # Note: These declarations are adapted from the standard prelude. @@ -16,8 +16,8 @@ pub type Result[T, E] = union Okay(T) Error(E) -## The Err interface. Useful for dynamically dispatching errors. -pub type Err = interface +## The Err class. Useful for dynamically dispatching errors. +pub type Err = class str(Self): str dbg(Self): str @@ -51,24 +51,25 @@ pub type Expr = ref union then_branch: Expr, else_branch: Expr) ## Evaluate an Expr down to a Value, or return an Error. -pub func eval(context: mut HashTable[Ident, Value], expr: Expr): Result[Value] +pub func eval(context: mut HashTable[Ident, Value], expr: Expr): Result[Value] = match expr - of Literal(value): Okay(value) - of Variable(ident): + of Literal(value) then Okay(value) + of Variable(ident) then context.get(ident) - .err("Could not find variable {} in context!".fmt(ident)) - of Application(body, arg): - if body of Abstraction(param, body as inner_body): + .err("Could not find variable {} in context!" + .fmt(ident)) + of Application(body, arg) then + if body of Abstraction(param, body as inner_body) then context.set(param, context.clone.eval(arg)?) context.eval(inner_body) - else: + else Error("Expected Abstraction, found body {} and argument {}".fmt(body, arg)) - of Conditional(condition, then_branch, else_branch): - if context.clone.eval(condition)? == "true": + of Conditional(condition, then_branch, else_branch) then + if context.clone.eval(condition)? == "true" then context.eval(then_case) - else: + else context.eval(else_case) - of _: Error("Invalid expression {}".fmt(expr)) + of _ then Error("Invalid expression {}".fmt(expr)) ``` </details> |