Merge branch 'master' of https://github.com/flaviut/nimrod-by-example

content/toc.md

@@ -4,6 +4,7 @@
 * [Hello World](/hello_world/)
 * [Variables](/variables/page/)
 * [Result](/variables/result/)
+* [Type Casting and Inference](/variables/type_casting_inference/)
 * [Objects](/objects/)
 * [Enums](/enums/)
 * [If, Else, While, Block](/if_else_while/)

content/variables/type_casting_inference.md

@@ -0,0 +1,35 @@
+---
+title: Type casting and inference
+---
+# Type casting and inference
+
+Nimrod is a statically typed language. As such, each variable has a type associated with it. As seen in the previous example these types are inferred in the `const`, `let` and `var` declarations by the compiler.
+
+```nimrod
+# These types are inferred.
+var x = 5 # int
+var y = "foo" # string
+
+# Assigning a value of a different type will result in a compile-time error.
+x = y
+```
+
+```console
+$ nimrod c -r typeinference.nim
+typeinference.nim(6, 4) Error: type mismatch: got (string) but expected 'int'
+```
+
+You may optionally specify the type after a colon (`:`). In some cases the compiler will expect you to explicitly cast types though. This can be done in two ways. One is to use "type conversion", this is the safe method, the compiler will ensure that it is safe to convert to that type. The other is to use the `cast` keyword, this is the unsafe method and should only be used when working with hardware or interfacing with C.
+
+```nimrod
+var x: int = int(1 / 3) # Type conversion. `/` returns a Float. The `: int` is superfluous.
+
+var y = "Foobar"
+proc ffi(foo: ptr array[6, char]) = echo repr(foo)
+ffi(cast[ptr array[6, char]](addr y[0]))
+```
+
+```console
+$ nimrod c -r typecasting.nim
+ref 002C8030 --> ['F', 'o', 'o', 'b', 'a', 'r']
+```