New simple static typing exercise

Author: jussienko

README.md

@@ -42,6 +42,7 @@ courses are stored in tags.
 ### Optimising with Cython
 
  - [Creating simple extension](cython/simple-extension)
+ - [Using static typing](cython/static-typing)
  - [Using C-functions](cython/c-functions)
  - [Optimising heat equation](cython/heat-equation)
 

cython/simple-extension/README.md

@@ -5,10 +5,11 @@ Create a simple Cython module (you can name it e.g. `cyt_module.pyx`)
 containing the following function:
 ```
 def subtract(x, y):
-    return x - y
+    result = x - y
+    return result
 ```
 
-Use the provided [setup.py](setup.py) for building the extension module.
+Create then a **setup.py** for building the extension module.
 Try to utilize the module e.g. as
 ```
 from cyt_module import subtract
@@ -18,10 +19,3 @@ subtract(4.5, 2)
 in interactive interpreter or in a simple script. Try different argument
 types.
 
-### Type declarations
-
-Declare the function arguments as **int** and rebuild the extension (Note: if working with interactive interpreter you need to exit or reload the module).
-What happens if you call now the subtract function with floating point
-arguments?
-
-

cython/simple-extension/solution/cyt_module.pyx

@@ -1,2 +1,3 @@
-def subtract(int x, int y):
-    return x - y
+def subtract(x, y):
+    result = x - y
+    return result

cython/static-typing/README.md

@@ -0,0 +1,21 @@
+## Using static typing 
+
+Continue with the simple Cython module for subtracting two numbers:
+```
+def subtract(x, y):
+    result = x - y
+    return result
+```
+
+Declare the function internal variable `result` as integer. Try to call the
+function with different types of arguments (integers and floats), what kind of
+results you do get?
+
+Next, declare also the function arguments as integers, and rebuild the module 
+(Note: if working with interactive interpreter you need to exit or
+reload the module). What happens when you now call the function with
+floating point arguments?
+
+Finally, try to declare arguments as floating point numbers (while keeping
+result as integer), what happens?
+

cython/static-typing/cyt_module.pyx

@@ -0,0 +1,3 @@
+def subtract(x, y):
+    result = x - y
+    return result

cython/simple-extension/setup.py renamed to cython/static-typing/setup.py

@@ -2,5 +2,5 @@
 from Cython.Build import cythonize
 
 setup(
-     ext_modules=cythonize("NAME-OF-MODULEFILE")
+     ext_modules=cythonize("cyt_module.pyx")
 )

cython/static-typing/solution/cyt_module.pyx

@@ -0,0 +1,4 @@
+def subtract(int x, int y):
+    cdef int result
+    result = x - y
+    return result

cython/static-typing/solution/setup.py

@@ -0,0 +1,6 @@
+from distutils.core import setup, Extension
+from Cython.Build import cythonize
+
+setup(
+     ext_modules=cythonize("cyt_module.pyx")
+)