Added style #5

05-shoot-your-teammate-forward/README.md

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+Style #5
+==============================
+
+Variation of style #4, with the following additional constraints:
+
+- Each function takes an additional parameter, usually the last, which is another function
+- That function parameter is applied at the end of the current function
+- That function parameter is given as input what would be the output of the current function
+- Larger problem is solved as a pipeline of functions, but where the next function to be applied is given as parameter to the current function
+
+Possible names:
+
+- Continuation-passing style
+- Crochet loop

05-shoot-your-teammate-forward/tf-05.py

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+import sys, re, operator, string
+
+#
+# The functions
+#
+def read_file(path_to_file, func):
+    """
+    Takes a path to a file and returns the entire
+    contents of the file as a string
+    """
+    f = open(path_to_file)
+    data = f.read()
+    f.close()
+    return func(data, normalize)
+
+def filter_chars(str_data, func):
+    """
+    Takes a string and returns a copy with all nonalphanumeric chars
+    replaced by white space
+    """
+    pattern = re.compile('[\W_]+')
+    return func(pattern.sub(' ', str_data), scan)
+
+def normalize(str_data, func):
+    """
+    Takes a string and returns a copy with all characters in lower case
+    """
+    return func(str_data.lower(), remove_stop_words)
+
+def scan(str_data, func):
+    """
+    Takes a string and scans for words, returning
+    a list of words.
+    """
+    return func(str_data.split(), frequencies)
+
+def remove_stop_words(word_list, func):
+    """ Takes a list of words and returns a copy with all stop words removed """
+    f = open('../stop_words.txt')
+    stop_words = f.read().split(',')
+    f.close()
+    # add single-letter words
+    stop_words.extend(list(string.ascii_lowercase))
+    return func([w for w in word_list if not w in stop_words], sort)
+
+def frequencies(word_list, func):
+    """
+    Takes a list of words and returns a dictionary associating
+    words with frequencies of occurrence
+    """
+    word_freqs = {}
+    for w in word_list:
+        if w in word_freqs:
+            word_freqs[w] += 1
+        else:
+            word_freqs[w] = 1
+    return func(word_freqs, no_op)
+
+def sort(word_freq, func):
+    """
+    Takes a dictionary of words and their frequencies
+    and returns a list of pairs where the entries are
+    sorted by frequency 
+    """
+    return func(sorted(word_freq.iteritems(), key=operator.itemgetter(1), reverse=True), None)
+
+def no_op(a, func):
+    return a
+
+#
+# The main function
+#
+word_freqs = read_file(sys.argv[1], filter_chars)
+
+for tf in word_freqs[0:25]:
+    print tf[0], ' - ', tf[1]
+