2 files changed, 106 insertions, 0 deletions
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;