doc: update E4162

Author: peter-jerry-ye

next/language/error_codes/E4162.md

@@ -0,0 +1,20 @@
+# E4162
+
+Local parameter is not function.
+
+`#locals` is an attribute that aims to inline the given function parameter. This
+error is raised when the given parameter is not a function.
+
+## Erroneous example
+
+```{literalinclude} /sources/error_codes/4162_error/top.mbt
+:language: moonbit
+```
+
+## Suggestion
+
+Apply `locals` to local functions only.
+
+```{literalinclude} /sources/error_codes/4162_fixed/top.mbt
+:language: moonbit
+```

next/sources/error_codes/4162_error/moon.mod.json

@@ -0,0 +1 @@
+{"name": "moonbit-community/E4162"}

next/sources/error_codes/4162_error/moon.pkg.json

@@ -0,0 +1 @@
+{}

next/sources/error_codes/4162_error/top.mbt

@@ -0,0 +1,11 @@
+///|
+#locals(init_)
+pub fn[A, B] fold(a : Array[A], init_~ : B, f : (B, A) -> B) -> B {
+  //                            ^
+  // This parameter is expected to be a function, but it is not.
+  let mut acc = init_
+  for x in a {
+    acc = f(acc, x)
+  }
+  acc
+}

next/sources/error_codes/4162_fixed/moon.mod.json

@@ -0,0 +1 @@
+{"name": "moonbit-community/E4162-fixed"}

next/sources/error_codes/4162_fixed/moon.pkg.json

@@ -0,0 +1 @@
+{}

next/sources/error_codes/4162_fixed/top.mbt

@@ -0,0 +1,9 @@
+///|
+#locals(f)
+pub fn[A, B] fold(a : Array[A], init_~ : B, f : (B, A) -> B) -> B {
+  let mut acc = init_
+  for x in a {
+    acc = f(acc, x)
+  }
+  acc
+}