From 953764004d241edb92de59c20437730785c41dab Mon Sep 17 00:00:00 2001
From: David Ashby <delta.mu.alpha@gmail.com>
Date: Sun, 21 Feb 2021 15:04:51 -0500
Subject: [PATCH] fix silly word collision with -1 built-in

---
 eval.go | 4 ++--
 main.go | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/eval.go b/eval.go
index 3542758..d65f424 100644
--- a/eval.go
+++ b/eval.go
@@ -72,13 +72,13 @@ func (c *Context) Exec(w Word) error {
 		// we have an implementation for that word. Run it.
 		err := w.Impl()
 		if err != nil {
-			return err
+			return fmt.Errorf("error during built-in: %w", err)
 		}
 	} else if len(w.Source) != 0 {
 		// user-defined word; let's descend...
 		err := c.Eval(strings.Join(w.Source, " ") + " ")
 		if err != nil {
-			return err
+			return fmt.Errorf("error during nested evaluation of word %+v: %w", w, err)
 		}
 	} else {
 		it, err := strconv.Atoi(w.Name)
diff --git a/main.go b/main.go
index c2351f4..6bc404f 100644
--- a/main.go
+++ b/main.go
@@ -41,8 +41,8 @@ func main() {
 	dict.AddWord("/", Word{Name: "/", Impl: b.Div(&stack)})
 	dict.AddWord("MOD", Word{Name: "MOD", Impl: b.Mod(&stack)})
 	dict.AddWord("/MOD", Word{Name: "/MOD", Source: []string{"2DUP", "MOD", "ROT", "ROT", "/"}})
-	dict.AddWord("+1", Word{Name: "+1", Source: []string{"1", "+"}})
-	dict.AddWord("-1", Word{Name: "-1", Source: []string{"1", "-"}})
+	dict.AddWord("1+", Word{Name: "1+", Source: []string{"1", "+"}})
+	dict.AddWord("1-", Word{Name: "1-", Source: []string{"1", "-"}})
 	dict.AddWord("ABS", Word{Name: "ABS", Source: []string{"DUP", "0<", "IF", "NEGATE", "THEN"}})
 	dict.AddWord("NEGATE", Word{Name: "NEGATE", Source: []string{"-1", "*"}})
 	dict.AddWord("MAX", Word{Name: "MAX", Source: []string{"2DUP", "<", "IF", "SWAP", "THEN", "DROP"}})