September Morn Update

Task/Function-composition/Python/function-composition-4.py

@@ -0,0 +1,43 @@
+from functools import reduce
+from numbers import Number
+import math
+
+
+def main():
+    '''Test'''
+
+    f = composeList([
+        lambda x: x / 2,
+        succ,
+        math.sqrt
+    ])
+
+    print(
+        f(5)
+    )
+
+
+# GENERIC FUNCTIONS ---------------------------------------
+
+
+# composeList :: [(a -> a)] -> (a -> a)
+def composeList(fs):
+    '''Composition, from right to left,
+       of a series of functions.'''
+    return lambda x: reduce(
+        lambda a, f: f(a),
+        fs[::-1],
+        x
+    )
+
+
+# succ :: Enum a => a -> a
+def succ(x):
+    '''The successor of a value. For numeric types, (1 +).'''
+    return 1 + x if isinstance(x, Number) else (
+        chr(1 + ord(x))
+    )
+
+
+if __name__ == '__main__':
+    main()