From 0609270d01b8f87e2c7579e91b43a6d0c2862f49 Mon Sep 17 00:00:00 2001
From: JJ
Date: Thu, 26 Oct 2023 14:51:27 -0700
Subject: compiler: draft of the abstract syntax tree

---
 src/ast.rs             | 105 +++++++++++++++++++++++++++++++++++++++++++++++++
 src/main.rs            |   1 +
 std/fundamental/ast.pk |  13 +++---
 3 files changed, 113 insertions(+), 6 deletions(-)
 create mode 100644 src/ast.rs

diff --git a/src/ast.rs b/src/ast.rs
new file mode 100644
index 0000000..92cabac
--- /dev/null
+++ b/src/ast.rs
@@ -0,0 +1,105 @@
+/// Representation of Tokens, function names, the like...
+pub type Id = String;
+
+/// Puck's fundamental types.
+pub enum Type {
+    Void, Never,
+    Integer, Float, String, // char et al are defined later
+    Func{from: Box<Type>, to: Box<Type>}, // todo: multiple params, effects
+    Struct(Vec<(Id, Box<Type>)>),
+    Tuple(Vec<(Option<String>, Box<Type>)>),
+    Union(Vec<(Id, Box<Type>)>),
+    Interface {
+        funcs: Vec<Sig>,
+        for_type: Option<Box<Type>>,
+    },
+    Array{size: usize, kind: Box<Type>},
+    List(Box<Type>),
+    Slice(Box<Type>), // todo: plus ownership
+    Reference(Box<Type>),
+    Mutable(Box<Type>), // parameters only
+    Static(Box<Type>),  // parameters only
+    Alias{ id: Id, params: Vec<Type> }, // todo: this is wrong
+}
+
+/// Function signatures.
+pub struct Sig {
+    effect: Option<Id>,
+    id: Id,
+    generics: Vec<(Id, Option<Type>)>,
+    params: Vec<Type>,
+    result: Option<Type>
+}
+
+/// Patterns are recognizable given zero context.
+/// This is why there is a generic Number term and no Bool term.
+/// Also can be considered to be a Term/Value.
+pub enum Pattern {
+    Ident(Id), // type aliases, union variants, calls...
+    Number(i64), Float(f64),
+    Char(char), String(String),
+    Struct(Vec<(Id, Expr)>),
+    Tuple(Vec<(Option<Id>, Expr)>),
+    List(Vec<Expr>), // arrays, slices, lists
+}
+
+/// Expressions introduce a new binding or bindings, in some regard.
+pub enum Binding {
+    Let {
+        // Most usages of Let, Var, Const have the id as just an Ident.
+        // But making it a Pattern supports ex. `let (a, b) = ...`
+        // And also unpacking: ex. `let Object(a, b) = ...`
+        id: Pattern,
+        kind: Option<Type>,
+        value: Box<Expr>
+    },
+    Var {
+        id: Pattern,
+        kind: Option<Type>,
+        value: Option<Box<Expr>> // variable bindings can be delayed
+    },
+    Const {
+        id: Pattern,
+        kind: Option<Type>,
+        value: Box<Expr>
+    },
+    Func {
+        public: bool,
+        effect: Option<Id>,
+        id: Id,
+        generics: Vec<(Id, Option<Type>)>,
+        params: Vec<(Id, Type)>,
+        kind: Type,
+        body: Vec<Expr>,
+    },
+    TypeDecl { id: Id, generics: Vec<Id>, alias: Type },
+    Import { from: Option<Id>, imports: Vec<Id>, alias: Option<Id> },
+    Module { id: Id, body: Vec<Expr> },
+}
+
+/// Expressions related to control flow.
+pub enum Control {
+    Call { id: Id, params: Vec<Expr> }, // function calls, macro invocations, field access...
+    Cond {
+        // cond, body
+        branches: Vec<(Expr, Vec<Expr>)>,
+        else_body: Option<Vec<Expr>>
+    },
+    Match {
+        item: Box<Expr>,
+        // pattern, guard, branch
+        branches: Vec<(Pattern, Option<Expr>, Expr)> // todo
+    },
+    Block { id: Option<Id>, body: Vec<Expr> },
+    Static { body: Vec<Expr> },
+    For { binding: Pattern, range: Box<Expr>, body: Vec<Expr> },
+    While { cond: Box<Expr>, body: Vec<Expr>, },
+    Loop { body: Vec<Expr> },
+}
+
+/// Expressions are either Patterns, Bindings, or Control flow constructs.
+pub enum Expr {
+    Pattern(Pattern),
+    Binding(Binding),
+    Control(Control),
+}
diff --git a/src/main.rs b/src/main.rs
index 5cbdf00..837dc1c 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,6 +1,7 @@
 #![allow(non_upper_case_globals)]
 #![feature(exclusive_range_pattern, let_chains)]
 
+mod ast;
 mod lex;
 mod tree;
 
diff --git a/std/fundamental/ast.pk b/std/fundamental/ast.pk
index 25bdc02..202c7d4 100644
--- a/std/fundamental/ast.pk
+++ b/std/fundamental/ast.pk
@@ -25,8 +25,8 @@ pub type FuncDecl = struct
   public: bool
   effect: Option[str]
   id: str
-  generics: list[struct[name: str, kind: Option[Type]]]
-  params: list[struct[name: str, kind: Type]]
+  generics: list[struct[id: str, kind: Option[Type]]]
+  params: list[struct[id: str, kind: Type]]
   kind: Type
   body: list[Expr]
 pub type TypeDecl = struct
@@ -38,8 +38,8 @@ pub type Import = struct
   imports: list[str]
   alias: Option[str]
 pub type Module = struct
-  name: str
-  body: list[ref Expr]
+  id: str
+  body: list[Expr]
 
 pub type Call = struct
   id: str
@@ -94,9 +94,10 @@ pub type Signature = struct # todo: generics
   kind: Option[Type]
 pub type Pattern = union
   Ident: str
-  Struct: struct[name: str, params: list[]]
+  Number: int, Float: float, Char: char, String: str
+  Struct: struct[name: str, params: list[Pattern]]
   Tuple: list[Pattern]
-  List
+  List: list[Pattern]
 pub type CondBranch = struct
   cond: Expr
   body: list[Expr]
-- 
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