From 56b21140e8d9cd1247ea064b9ce3fdbe2f8b57ec Mon Sep 17 00:00:00 2001
From: Gabriel Kerneis
Date: Wed, 11 Jun 2014 15:15:38 +0100
Subject: Improve error message for missing library functions

---
 src/lem_interp/interp_lib.lem | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

(limited to 'src')

diff --git a/src/lem_interp/interp_lib.lem b/src/lem_interp/interp_lib.lem
index 18af8bfd..4d6ae138 100644
--- a/src/lem_interp/interp_lib.lem
+++ b/src/lem_interp/interp_lib.lem
@@ -1,7 +1,7 @@
 open import Pervasives
 open import Interp
 open import Interp_ast
-import Maybe_extra
+import Assert_extra Maybe_extra
 open import Num
 open import List
 open import Word
@@ -161,4 +161,7 @@ let function_map = [
   ("gt_vec", compare_op_vec (>));
 ] ;;
 
-let eval_external name v = (Maybe_extra.fromJust (List.lookup name function_map)) v ;;
+let eval_external name v = match List.lookup name function_map with
+  | Just f -> f v
+  | Nothing -> Assert_extra.failwith ("missing library function " ^ name)
+  end
-- 
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