From e9a4a928f05084d311b9d9e2c31f4f1d9fa1dcb6 Mon Sep 17 00:00:00 2001
From: milesfrain <milesfrain@users.noreply.github.com>
Date: Fri, 1 Jan 2021 22:39:34 -0800
Subject: [PATCH] Add more examples for anonymous argument error

---
 errors/IncorrectAnonymousArgument.md | 41 ++++++++++++++++++++++------
 1 file changed, 32 insertions(+), 9 deletions(-)

diff --git a/errors/IncorrectAnonymousArgument.md b/errors/IncorrectAnonymousArgument.md
index e377eae3..7aadee61 100644
--- a/errors/IncorrectAnonymousArgument.md
+++ b/errors/IncorrectAnonymousArgument.md
@@ -5,31 +5,54 @@
 ```purescript
 module Example where
 
-add = (_ + _)
+sub3 = _ - 3
 
-mapArray = map _ [1, 2, 3]
+square = (_ * _)
+result1 = map (_ * _) [1, 2, 3]
+
+result2 = map (div _ 2) [1, 2, 3]
+
+result3 = map (1 + _ / 2) [1, 2, 3]
 ```
 
 ## Cause
 
-In an [operator section](https://github.com/purescript/documentation/blob/fc4a9db4b128aa3331e5f990cb1860e59077af31/language/Syntax.md#operator-sections), like `(_ + 1)`, an anonymous argument can be used only once.
-
+An [operator section](https://github.com/purescript/documentation/blob/master/language/Syntax.md#operator-sections), like `(_ + 1)`, has the following requirements:
+- The expression must be bracketed (surrounded by parens).
+- An anonymous argument can be used only once.
+- The anonymous argument must neighbor a [binary operator](https://github.com/purescript/documentation/blob/master/language/Syntax.md#binary-operators).
+- The anonymous argument must be the _sole expression_ for one of the binary operator arguments.
 
 ## Fix
 
-In the case of multiple arguments, give them names:
+Surround with parens:
 ```purescript
-add a b = (a + b)
+sub3 = (_ - 3)
 ```
-or in the case of a normal function: Write the function [as an operator](https://github.com/purescript/documentation/blob/fc4a9db4b128aa3331e5f990cb1860e59077af31/language/Syntax.md#functions-as-operators) using backticks:
+
+Replace multiple anonymous arguments with named arguments: 
 ```purescript
-mapArray = _ `map` [1, 2, 3]
+square a = a * a
+result1 = map (\n -> n * n) [1, 2, 3]
 ```
 
+Write the function [as an operator](https://github.com/purescript/documentation/blob/master/language/Syntax.md#functions-as-operators) using backticks:
+```purescript
+result2 = map (_ `div` 2) [1, 2, 3]
+```
+or simply use the corresponding infix operator if one is available:
+```purescript
+result2 = map (div _ 2) [1, 2, 3]
+```
+
+Replace the anonymous argument with a named argument: 
+```purescript
+result3 = map (\n -> 1 + n / 2) [1, 2, 3]
+```
 
 ## Notes
 
-- While `_ + _` will give this error; `\a -> a + _` will not
+- While `(_ + _)` will give this error; `\a -> (a + _)` will not
 
 - If you really want to have multiple anonymous arguments, it can be achieved like this:
 ```purescript