start work on type resolver

src/namespace/command.rs

@@ -18,6 +18,18 @@ impl<'a> Command<'a> {
             .as_ref()
             .map(|def| TypeDef::from_internal(self.namespace, def))
     }
+    // get a count of inputs required
+    pub fn input_count(&self) -> usize {
+        self.namespace.commands.borrow()[self.id]
+            .input
+            .as_ref()
+            .map(|inputs| match inputs {
+                InternalTypeDef::Single(_) => 1,
+                InternalTypeDef::List(list) => list.len(),
+                InternalTypeDef::Record(rec) => rec.len(),
+            })
+            .unwrap_or(0)
+    }
     pub fn get_output_types(&self) -> Option<TypeDef> {
         self.namespace.commands.borrow()[self.id]
             .output

src/namespace/typedef.rs

@@ -101,6 +101,18 @@ impl Debug for TypeDef<'_> {
     }
 }
 
+impl<'a> From<Type<'a>> for TypeDef<'a> {
+    fn from(value: Type<'a>) -> Self {
+        TypeDef::Type(value)
+    }
+}
+
+impl<'a> From<Trait<'a>> for TypeDef<'a> {
+    fn from(value: Trait<'a>) -> Self {
+        TypeDef::Trait(value)
+    }
+}
+
 pub(super) enum InternalTypeDef {
     Single(TypeNamespaceId),
     List(Vec<InternalTypeDef>),

src/typed.rs

@@ -1,9 +1,15 @@
 use core::panic;
+use std::process::CommandEnvs;
 
 use crate::{
     builtins::{TYPE_FLOAT, TYPE_INTEGER, TYPE_STRING},
     error::Errors,
-    namespace::{command::Command, r#type::Type, GlobalNamespace},
+    namespace::{
+        command::{self, Command},
+        r#type::Type,
+        typedef::TypeDef,
+        GlobalNamespace,
+    },
     syntax::{CommandPart, CommandPartKind, PipelineElement, PipelineElementKind},
     Span,
 };
@@ -15,15 +21,59 @@ pub struct Expr<'a> {
     span: Span,
 }
 
+impl<'a> Expr<'a> {
+    fn try_find_concrete(&'a self, ns: &'a GlobalNamespace) -> IoTypes<'a> {
+        let Self { ref kind, .. } = self;
+        kind.try_find_concrete(ns)
+    }
+
+    fn get_input_typedef(&'a self) -> Option<TypeDef<'a>> {
+        match &self.kind {
+            ExprKind::Command(c) => c.command.get_input_types(),
+            ExprKind::Literal(_) => None,
+        }
+    }
+}
+
 #[derive(Debug)]
 pub enum ExprKind<'a> {
-    Command {
+    Command(CommandExpr<'a>),
-        command: Command<'a>,
-        args: Vec<Expr<'a>>,
-    },
     Literal(LiteralKind),
 }
 
+impl<'a> ExprKind<'a> {
+    fn try_find_concrete(&'a self, ns: &'a GlobalNamespace) -> IoTypes<'a> {
+        match self {
+            ExprKind::Literal(lit) => IoTypes::Concrete(lit.get_type(ns)),
+            ExprKind::Command(c) => c.try_find_concrete(ns),
+        }
+    }
+}
+
+#[derive(Debug)]
+struct CommandExpr<'a> {
+    command: Command<'a>,
+    args: Vec<Expr<'a>>,
+}
+
+impl<'a> CommandExpr<'a> {
+    fn try_find_concrete(&'a self, ns: &'a GlobalNamespace) -> IoTypes<'a> {
+        let Self { command, args } = self;
+
+        match command.get_output_types() {
+            None => IoTypes::Empty,
+            Some(def) => {
+                if let Some(concrete) = ConcreteTypeDef::try_from_typedef(&def) {
+                    IoTypes::Concrete(concrete)
+                } else {
+                    // TODO: make it possible to get clear output type
+                    IoTypes::Unclear
+                }
+            }
+        }
+    }
+}
+
 #[derive(Debug)]
 pub enum LiteralKind {
     Int(i64),
@@ -31,17 +81,26 @@ pub enum LiteralKind {
     String(String),
 }
 
+enum IoTypes<'a> {
+    /// expression does not expect/return anything
+    Empty,
+    /// expression does expect/return something, but some types are unclear
+    Unclear,
+    /// we know for sure what types the expression expects/returns
+    Concrete(ConcreteTypeDef<'a>),
+}
+
 impl LiteralKind {
     #[allow(
         clippy::unwrap_used,
         reason = "these are fetched by type name constants used for keeping names consistent in codebase, which cannot be None"
     )]
-    pub fn get_type<'a>(&self, ns: &'a GlobalNamespace) -> Type<'a> {
+    pub fn get_type<'a>(&self, ns: &'a GlobalNamespace) -> ConcreteTypeDef<'a> {
-        match self {
+        ConcreteTypeDef::Single(match self {
             LiteralKind::Int(_) => ns.get_type_by_name(TYPE_INTEGER).unwrap(),
             LiteralKind::Float(_) => ns.get_type_by_name(TYPE_FLOAT).unwrap(),
             LiteralKind::String(_) => ns.get_type_by_name(TYPE_STRING).unwrap(),
-        }
+        })
     }
 }
 
@@ -61,7 +120,7 @@ pub fn into_typed_repr(
 
                     res.push(Expr {
                         kind: match kind {
-                            CommandPartKind::Word(val) => ExprKind::Command {
+                            CommandPartKind::Word(val) => ExprKind::Command(CommandExpr {
                                 command: {
                                     let Some(c) = ns.get_command_by_name(val) else {
                                         errs.push(span);
@@ -70,7 +129,7 @@ pub fn into_typed_repr(
                                     c
                                 },
                                 args: Vec::new(),
-                            },
+                            }),
                             CommandPartKind::Integer(val) => {
                                 ExprKind::Literal(LiteralKind::Int(*val))
                             }
@@ -93,7 +152,7 @@ pub fn into_typed_repr(
                     };
 
                     res.push(Expr {
-                        kind: ExprKind::Command {
+                        kind: ExprKind::Command(CommandExpr {
                             command: {
                                 let Some(c) = ns.get_command_by_name(name) else {
                                     errs.push(span.clone());
@@ -116,7 +175,7 @@ pub fn into_typed_repr(
                                     span: span.clone(),
                                 })
                                 .collect(),
-                        },
+                        }),
                         span: span.clone(),
                     });
                 }
@@ -131,3 +190,60 @@ pub fn into_typed_repr(
         Err(Errors::new(crate::error::ErrorKind::CommandNotFound, errs))
     }
 }
+
+enum ConcreteTypeDef<'a> {
+    Single(Type<'a>),
+    List(Vec<ConcreteTypeDef<'a>>),
+    Record(Vec<(String, ConcreteTypeDef<'a>)>),
+}
+
+impl<'a> ConcreteTypeDef<'a> {
+    fn try_from_typedef(val: &TypeDef<'a>) -> Option<Self> {
+        match val {
+            TypeDef::Type(typ) => Some(Self::Single(*typ)),
+            TypeDef::Trait(_) => None,
+            TypeDef::List(list) => {
+                let out: Vec<ConcreteTypeDef<'a>> =
+                    list.iter().filter_map(Self::try_from_typedef).collect();
+
+                (out.len() == list.len()).then_some(ConcreteTypeDef::List(out))
+            }
+            TypeDef::Record(rec) => {
+                let out: Vec<(String, ConcreteTypeDef<'a>)> = rec
+                    .iter()
+                    .filter_map(|(name, def)| {
+                        Self::try_from_typedef(def).map(|def| (name.clone(), def))
+                    })
+                    .collect();
+
+                (out.len() == rec.len()).then_some(ConcreteTypeDef::Record(out))
+            }
+        }
+    }
+}
+
+struct TypeChecker<'a> {
+    global_ns: &'a GlobalNamespace,
+    typed_syntax: Vec<Expr<'a>>,
+}
+
+impl<'a> TypeChecker<'a> {
+    fn new(ns: &'a GlobalNamespace, syntax: Vec<Expr<'a>>) -> TypeChecker<'a> {
+        Self {
+            global_ns: ns,
+            typed_syntax: syntax,
+        }
+    }
+
+    // not sure if this is the optimal alg, or even a working one, but lets see
+    fn check_forward(&self) {
+        let i = 0;
+
+        // loop {
+        //     let maybe_concrete = match self.typed_syntax[i].kind {
+        //         ExprKind::Literal(l) => todo!(),
+        //         ExprKind::Command(c) => todo!(),
+        //     }
+        // }
+    }
+}