Changeset 184

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• docs/trunk/hacking-guide/tock-intro.tex

  r183	r184
  359	359	code would be faster. The compiler does not have to be blindingly fast, but it does need to be
  360	360	maintainable.
  361	\item If a function foo is specifically needed by only the function bar, place foo inside the (削除) where (削除ここまで)
  361	\item If a function foo is specifically needed by only the function bar, place foo inside the (追記) \lstinline|where| (追記ここまで)
  362	362	clause of bar (unless this is particularly untenable). This keeps the code neater, and foo can always
  363	363	be moved to the top-level later if necessary.
  364	\item Try to provide type signatures for every function (i.e. anything of (削除) type a -> b -> c) in a where clause. (削除ここまで)
  365	(削除) Providing types for values in where clauses (削除ここまで) is also never a bad thing.
  364	\item Try to provide type signatures for every function (i.e. anything of (追記) kind \lstinline|* -> *|) in a (追記ここまで)
  365	(追記) \lstinline|where| clause. Providing types for values in where \lstinline|clauses| (追記ここまで) is also never a bad thing.
  366	366	\item Favour map, zip, etc over list comprehensions; it is usually neater.
  367	(追記) \item Try not to leave warnings in the code. We have compiler options turned on to generate various warnings. (追記ここまで)
  368	(追記) Defaulting-to-type warnings can be solved by inserting a type signature, and unused binding warnings can (追記ここまで)
  369	(追記) be solved by removing the unused function, unless you know the lack of used is temporary. (追記ここまで)
  367	370	\item Never allow any possibility of a non-graceful run-time error. For example, do not use head, which
  368	can fail directly with a non-helpful error message. Instead, use a (削除) case statement (with a pattern-match), (削除ここまで)
  369	and in the case where the list is empty, use the die/dieP/dieInternal functions to provide a more helpful
  370	(削除) (削除ここまで)error message (such as ``list of types was not expected to be empty in function foo''). This is for
  371	can fail directly with a non-helpful error message. Instead, use a (追記) \lstinline|case| statement (with a (追記ここまで)
  372	pattern-match), and in the case where the list is empty, use the die/dieP/dieInternal functions to provide a
  373	(追記) more helpful (追記ここまで)error message (such as ``list of types was not expected to be empty in function foo''). This is for
  371	374	practical reasons; if we used head everywhere in the code, then when the program failed with ``head: empty list''
  372	375	it would be very hard to work out exactly which instance of head had given the error. Similarly, try to
  …	…
  374	377	then gives an error message. Although this is not quite as crucial, because at least the error message
  375	378	for a failed pattern match gives the relevant line numbers.
  379	(追記) \item In lists where order is unimportant (such as test lists, or module import lists), maintain (追記ここまで)
  380	(追記) alphabetical order (to make it easier to find items in a long list). (追記ここまで)
  381	(追記) \item When writing out lists or tuples on one line, make sure there is a space after the comma (clearer, (追記ここまで)
  382	(追記) and Adam's preference). (追記ここまで)
  383	(追記) \item When writing out lists on several lines, put the commas between items at the beginning of each line, (追記ここまで)
  384	(追記) not at the end (can make patches clearer by not disrupting surrounding lines and Neil's preference). (追記ここまで)
  376	385	\end{enumerate}
  377	386

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