further corrections(?) #137
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Thanks, I'll carefully review this pr later today |
| case, the result of the function is zero. Another possible view on | ||
| \C{subn} it to see it as a subtraction operation on natural numbers, | ||
| made total by providing a default value in the ``exceptional'' cases. | ||
| case, the result of the function is zero. We can view |
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The change goes on for a few more lines -- I reworded rather than removed this sentence. I was trying to remove the word "exceptional" since I found it somewhat counterintuitive to think of 1/2 of all possible inputs as "exceptional". But I don't have a strong preference either way.
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Another way to state this behavior precisely is saying that the subtraction is truncated at 0. See monus.
tex/chProgramming.tex
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| @@ -1375,7 +1386,7 @@ \subsection{The (polymorphic) sequence data type} | |||
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| The name \C{seq} refers to (finite) ``sequences'', also called | |||
| ``lists''. This definition actually describes the type | |||
| ``lists''. This definition describes the type | |||
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What does the word "actually" mean for you? To me it means that we are making things more correct or more precise, so I don't understand its meaning in this sentence (there is nothing wrong about "sequences" or "lists").
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Sorry, one of my comment was misplaced. I hope it is correct now.
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"actually" refers to the fact "seq" is only a synonym for "list".
The situation is not very satisfactory, because if we type "Print list." in Coq, we get the following text:
Inductive list (A : Type) : Type := nil : seq A | cons : A -> seq A -> seq A
So "list" is used in the first part, and "seq" is used after the ":=" characters. This is messy at best.
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@darijgr I had a little chat with @ybertot and we believe that the best way forward for this PR is that you split into two parts: one containing the minor fixes, typos, etc which can be merged fast, and another one with the last big chunk which requires more thinking, especially on our side (the book was written a long ago, we need to put your change into context to review it). Thanks again for your contribution. |
…derstanding.
* Again, \C{compute} -> \C{Compute} since the two are not the same (right?) and it is the latter that is being used.
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@gares Done what you said. Now this branch has the relatively straightforward edits, whereas the implicit argument rewrite is at https://github.com/darijgr/mcb/tree/sugg2b . |
tex/chProgramming.tex
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| case, the result of the function is zero. We can view | ||
| \C{subn} as a subtraction operation on natural numbers, artificially | ||
| made total by providing a default value in the cases where it would | ||
| normally produce a negative number. |
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This is misleading, IMO, because "subtraction operation on natural numbers" cannot "produce a negative number".
I think that both "made total" and "truncated" are good ways to express what it does.
As a CS person, I clearly see total as more natural, but if a reference to truncated subtraction can help the Math inclined reader I suggest we have both.
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What do you think of the new version?
More little examples and parentheticals to help the reader check understanding.
Again, \C{compute} -> \C{Compute} since the two are not the same (right?) and it is the latter that is being used.
I think the syntactic sugar in the definition of same_bool is expanded more like I suggest than like the previous text suggests (even though the resulting functions, of course, are
equivalent). Is that so?
Experimental rewrite of the paragraphs on implicit argument. Currently, "About cons" does NOT say anything about "implicit" or "maximally inserted" arguments (at least not on my
installation). Thus I removed the mention of "About" here (it should be introduced somewhere, maybe in a separate subsection about Evaluate, Search, About and friends). On the
other hand, I have added the (A := U) notation for manually providing implicit arguments.