From 6beccd09a8f020b12f1cf8736ee8ea651cca0f9a Mon Sep 17 00:00:00 2001
From: Sander Spies <sandermail@gmail.com>
Date: Sun, 2 Feb 2020 18:08:16 +0100
Subject: [PATCH] Wrong function arguments error message.

---
 src/bin/expect_tests/syntax_error_tests.ml    | 19 +++++++++++++++++++
 src/passes/1-parser/reasonligo.ml             |  9 ++++++++-
 .../negative/error_function_arguments.religo  |  2 ++
 3 files changed, 29 insertions(+), 1 deletion(-)
 create mode 100644 src/test/contracts/negative/error_function_arguments.religo

diff --git a/src/bin/expect_tests/syntax_error_tests.ml b/src/bin/expect_tests/syntax_error_tests.ml
index bf835d78b..0d29a80d1 100644
--- a/src/bin/expect_tests/syntax_error_tests.ml
+++ b/src/bin/expect_tests/syntax_error_tests.ml
@@ -15,3 +15,22 @@ let%expect_test _ =
     * Open a gitlab issue: https://gitlab.com/ligolang/ligo/issues/new
     * Check the changelog by running 'ligo changelog' |} ] ;
 
+  run_ligo_bad [ "compile-contract" ; "../../test/contracts/negative/error_function_arguments.ligo" ; "main" ] ;
+  [%expect {|
+    ligo: in file "basic.religo", line 1, characters 14-27. : It looks like you are defining a function, however we do not
+      understand the parameters declaration.
+      Examples of valid functions:
+      let x = (a: string, b: int) : int => 3;
+      let tuple = ((a, b): (int, int)) => a + b; 
+      let x = (a: string) : string => "Hello, " ++ a;
+       {"location":"in file \"basic.religo\", line 1, characters 14-27"}
+      
+
+     If you're not sure how to fix this error, you can
+     do one of the following:
+
+    * Visit our documentation: https://ligolang.org/docs/intro/what-and-why/
+    * Ask a question on our Discord: https://discord.gg/9rhYaEt
+    * Open a gitlab issue: https://gitlab.com/ligolang/ligo/issues/new
+    * Check the changelog by running 'ligo changelog' |} ] ;
+
diff --git a/src/passes/1-parser/reasonligo.ml b/src/passes/1-parser/reasonligo.ml
index 17091363b..5254018e8 100644
--- a/src/passes/1-parser/reasonligo.ml
+++ b/src/passes/1-parser/reasonligo.ml
@@ -55,7 +55,14 @@ module Errors =
 
     let wrong_function_arguments (expr: AST.expr) =
       let title () = "" in
-      let message () = "Wrong function arguments.\n" in
+      let message () = "It looks like you are defining a function, \
+               however we do not\n\
+               understand the parameters declaration.\n\
+               Examples of valid functions:\n\
+               let x = (a: string, b: int) : int => 3;\n\
+               let tuple = ((a, b): (int, int)) => a + b; \n\
+               let x = (a: string) : string => \"Hello, \" ++ a;\n" 
+      in
       let expression_loc = AST.expr_to_region expr in
       let data = [
         ("location",
diff --git a/src/test/contracts/negative/error_function_arguments.religo b/src/test/contracts/negative/error_function_arguments.religo
new file mode 100644
index 000000000..b80d7f002
--- /dev/null
+++ b/src/test/contracts/negative/error_function_arguments.religo
@@ -0,0 +1,2 @@
+let div = (a, b : nat * nat) : option (nat) =>
+  if (b == 0n) { None; } else { Some (a/b); }
\ No newline at end of file