Euler's sum of powers conjecture: Difference between revisions

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@@ Line 3,070: / Line 3,070: @@
-# GENERIC -------------------------------------------------
+# ----------------------- GENERIC ------------------------
 # Just :: a -> Maybe a
 def Just(x):
-    '''Constructor for an inhabited Maybe (option type) value.'''
+    '''Constructor for an inhabited Maybe (option type) value.
+       Wrapper containing the result of a computation.
+    '''
     return {'type': 'Maybe', 'Nothing': False, 'Just': x}
-# Nothing :: Maybe a
+# Nothing :: () -> Maybe a
 def Nothing():
-    '''Constructor for an empty Maybe (option type) value.'''
+    '''Constructor for an empty Maybe (option type) value.
+       Empty wrapper returned where a computation is not possible.
+    '''
     return {'type': 'Maybe', 'Nothing': True}
@@ Line 3,092: / Line 3,095: @@
        passed as an argument to the second.
     '''
+    def go(f):
-    return lambda f: chain.from_iterable(map(f, xs))
+        return chain.from_iterable(map(f, xs))
+    return go
@@ Line 3,104: / Line 3,109: @@
 def find(p):
     '''Just the first element in the list that matches p,
-       or Nothing if no elements match.'''
+       or Nothing if no elements match.
+    '''
     def go(xs):
-        for x in xs:
+        try:
-            if p(x):
+            return Just(next(x for x in xs if p(x)))
-                return Just(x)
+        except StopIteration:
-        return Nothing()
+            return Nothing()
-    return lambda xs: go(xs)
+    return go
@@ Line 3,117: / Line 3,123: @@
     '''Either the default value v, if m is Nothing,
        or the application of f to x,
-       where m is Just(x).'''
+       where m is Just(x).
+    '''
-    return lambda f: lambda m: v if m.get('Nothing') else (
-        f(m.get('Just'))
+    return lambda f: lambda m: v if (
+        None is m or m.get('Nothing')
-    )
+    ) else f(m.get('Just'))