Documentation updates

docs/assignments.md

@@ -0,0 +1,79 @@
+# Assignments
+
+Brighterscript allows you to declare the type of variables in the assignment, with using the `as <type>` syntax on the left hand side of the `=` (equals).
+
+Keep in mind that this is the type as BrighterScript understands it to be. The actual type during runtime may be different. Even with this caveat, by declaring types in assignments, the risk of runtime errors because of invalid type usage is lessened.
+
+## Example
+
+In the following example, `data` is `dynamic` type, but we declare that `name` is of `string` type:
+
+```brighterscript
+function getUCaseName(data) as string
+    name as string = data.name
+
+    return ucase(name)
+end function
+```
+
+## Validation
+
+By declaring the type on the left hand side of the assignment, if the inferred type of the right hand side is not compatible, an error message is raised:
+
+```brighterscript
+sub assignmentValidation()
+    pi as float = 3.14 ' no error: 3.14 is a float
+
+    twoPi as integer = pi * 2 ' no error: numbers are always compatible
+
+    boolTest as bool = "true" ' error: strings are not compatible with boolean
+
+    data as {id as string} = {id: 1234} ' error: "id" member not compatible
+
+    deviceInfo as string = createObject("roDeviceInfo") ' error: types not compatible
+end sub
+```
+
+## Declared Type vs. Typecast
+
+Declaring a type in an assignment is very similar to using a [typecast](./typecasts.md) on the right hand side, with one major difference: typecasts are not validated. Therefore it is safer to use declared types if possible.
+
+Example:
+
+```brighterscript
+sub exampleTypecast()
+    name = 1234 as string ' No BrighterScript error
+    print ucase(name) ' Runtime error: name is an integer
+end sub
+
+sub exampleDeclaredType()
+    name as string = 1234 ' BrighterScript error - types not compatible
+    print ucase(name) ' Would be runtime error, but previous line caught during compilation
+end sub
+```
+
+## For each loop variables
+
+The type of a `for each` loop item can be declared as well:
+
+```brighterscript
+function sumWidthArray(widthArray) as integer
+    total = 0
+    for each width as integer in widthArray
+       total += width ' width is an integer
+    end for
+    return total
+end function
+```
+
+If the declared type is not compatible with the inferred type, an error will be raised. In this example, the declared item type is `integer`, but iterating over a `roAssociativeArray` will give the `string` values of the keys of the associative array:
+
+```brighterscript
+function sumWidthMap(widthMap as roAssociativeArray) as integer
+    total = 0
+    for each width as integer in widthMap ' error
+       total += width
+    end for
+    return total
+end function
+```

docs/intersection-types.md

@@ -37,8 +37,8 @@ interface HasSize
 end interface
 
 
-function getUrlWithQuerySize(response as HasId and HasUrl and HasSize) as string
-    return value.url + "?id=" + value.id + "&w=" + value.width.toStr().trim() + "&h=" + value.height.toStr().trim()
+function getUrlWithQuerySize(value as HasUrl and HasId and HasSize) as string
+    return value.url + `?id=${value.id}&w=${value.width}&h=${value.height}`
 end function
 ```
 

docs/readme.md

@@ -7,17 +7,30 @@ See the following pages for more information:
 ## [Annotations](annotations.md)
 
 ```brighterscript
-'mostly useful for plugins that change code based on annotations
+' mostly useful for plugins that change code based on annotations
 @logOnException()
 sub doSomething()
     '...
-end
+end sub
+```
+
+## [Assignments](assigments.md)
+
+```brighterscript
+' declare the type of variables
+sub showTypedAssignments()
+    name as string = getData()
+
+    for each item as integer in getDurationSeconds(name)
+        print "Time in MS:"; item / 1000
+    end for
+end sub
 ```
 
 ## [Callfunc Operator](callfunc-operator.md)
 
 ```brighterscript
-'instead of `node.callfunc("someMethod", 1, 2, 3)`, you can do this:
+' instead of `node.callfunc("someMethod", 1, 2, 3)`, you can do this:
 node@.someMethod(1, 2, 3)
 ```
 
@@ -61,7 +74,7 @@ end enum
 ```brighterscript
 try
     somethingDangerous()
-catch 'look, no exception variable!
+catch ' look, no exception variable!
     print "Living on the edge!"
 end try
 ```