gbf @ a3c25d0

M src/gbf/eval.gleam

@@ -11,7 +11,7 @@ /// An unexpected command was encountered at the given position.
   UnexpectedCommand(pos: lexer.Position)
 
   /// An error occurred in the virtual machine
-  VmError(reason: vm.Error)
+  VmError(reason: vm.Error, pos: lexer.Position)
 }
 
 /// Evaluates an AST node against the virtual machine.
@@ -28,20 +28,22 @@ command: Command,
   vm: VirtualMachine,
 ) -> Result(VirtualMachine, Error) {
   case command {
-    #(token.IncrementPointer, _) ->
-      vm.set_pointer(vm, vm.pointer + 1) |> wrap_vm_error()
-    #(token.DecrementPointer, _) ->
-      vm.set_pointer(vm, vm.pointer - 1) |> wrap_vm_error()
+    #(token.Comment(_), _) -> Ok(vm)
+
+    #(token.IncrementPointer, p) ->
+      vm.set_pointer(vm, vm.pointer + 1) |> wrap_vm_error(p)
+    #(token.DecrementPointer, p) ->
+      vm.set_pointer(vm, vm.pointer - 1) |> wrap_vm_error(p)
 
-    #(token.IncrementByte, _) -> mut_byte(vm, int.add)
-    #(token.DecrementByte, _) -> mut_byte(vm, int.subtract)
+    #(token.IncrementByte, p) -> mut_byte(vm, int.add) |> wrap_vm_error(p)
+    #(token.DecrementByte, p) -> mut_byte(vm, int.subtract) |> wrap_vm_error(p)
 
-    #(token.InputByte, _) -> vm.input_byte(vm) |> wrap_vm_error
-    #(token.OutputByte, _) -> vm.output_byte(vm) |> wrap_vm_error
+    #(token.InputByte, p) -> vm.input_byte(vm) |> wrap_vm_error(p)
+    #(token.OutputByte, p) -> vm.output_byte(vm) |> wrap_vm_error(p)
 
-    #(token.StartBlock, pos) -> Error(UnexpectedCommand(pos))
-    #(token.EndBlock, pos) -> Error(UnexpectedCommand(pos))
-    #(_, pos) -> Error(UnexpectedCommand(pos))
+    #(token.StartBlock, p) -> Error(UnexpectedCommand(p))
+    #(token.EndBlock, p) -> Error(UnexpectedCommand(p))
+    #(_, p) -> Error(UnexpectedCommand(p))
   }
 }
 
@@ -57,7 +59,7 @@
 fn eval_child_block(vm: VirtualMachine, child_block: Block) {
   use cell_value <- result.try(
     vm.get_cell(vm, vm.pointer)
-    |> result.map_error(VmError),
+    |> result.map_error(VmError(_, pos: child_block.position)),
   )
 
   case cell_value > 0 {
@@ -70,18 +72,15 @@ }
 }
 
 fn mut_byte(vm: VirtualMachine, op: fn(Int, Int) -> Int) {
-  use cell_value <- result.try(
-    vm.get_cell(vm, vm.pointer)
-    |> result.map_error(VmError),
-  )
+  use cell_value <- result.try(vm.get_cell(vm, vm.pointer))
 
   let cell_value = op(cell_value, 1)
   vm.set_cell(vm, vm.pointer, cell_value)
-  |> result.map_error(VmError)
 }
 
 fn wrap_vm_error(
   r: Result(VirtualMachine, vm.Error),
+  pos: lexer.Position,
 ) -> Result(VirtualMachine, Error) {
-  result.map_error(r, VmError)
+  result.map_error(r, VmError(_, pos))
 }