Comma quibbling

Comma quibbling is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.

Comma quibbling is a task originally set by Eric Lippert in his blog.

The task is to write a function to generate a string output which is the concatenation of input words from a list/sequence where:

1. An input of no words produces the output string of just the two brace characters "{}".
2. An input of just one word, e.g. ["ABC"], produces the output string of the word inside the two braces, e.g. "{ABC}".
3. An input of two words, e.g. ["ABC", "DEF"], produces the output string of the two words inside the two braces with the words separated by the string " and ", e.g. "{ABC and DEF}".
4. An input of three or more words, e.g. ["ABC", "DEF", "G", "H"], produces the output string of all but the last word separated by ", " with the last word separated by " and " and all within braces; e.g. "{ABC, DEF, G and H}".

Test your function with the following series of inputs showing your output here on this page:

• [] # (No input words).
• ["ABC"]
• ["ABC", "DEF"]
• ["ABC", "DEF", "G", "H"]

Note: Assume words are non-empty strings of uppercase characters for this task.

Python

<lang python>>>> def strcat(sequence): # replace(..) can only replace the first X occurrences not the last # Hence the replace is done on the reverse of the intermediate string # then reversed back. return '{%s}' % ', '.join(sequence)[::-1].replace(',', 'dna ', 1)[::-1]

>>> for seq in ([], ["ABC"], ["ABC", "DEF"], ["ABC", "DEF", "G", "H"]): print('Input: %-24r -> Output: %r' % (seq, strcat(seq)))

Input: [] -> Output: '{}' Input: ['ABC'] -> Output: '{ABC}' Input: ['ABC', 'DEF'] -> Output: '{ABC and DEF}' Input: ['ABC', 'DEF', 'G', 'H'] -> Output: '{ABC, DEF, G and H}' >>> </lang>