Comments on: Code Safety and Correctness is a matter of Mindset Cultured by the Language http://sadekdrobi.com/2008/11/02/code-safety-and-correctness-is-a-matter-of-mindset-cultured-by-the-language/ Sadek Drobi Mon, 02 Nov 2009 05:56:20 +0100 http://wordpress.org/?v=2.8.2 hourly 1 By: Sadache http://sadekdrobi.com/2008/11/02/code-safety-and-correctness-is-a-matter-of-mindset-cultured-by-the-language/comment-page-1/#comment-5596 Sadache Thu, 06 Nov 2008 17:32:13 +0000 http://sadekdrobi.com/2008/11/02/code-safety-and-correctness-is-a-matter-of-mindset-cultured-by-the-language/#comment-5596 @Fran I was referring to reads that "Normally, [] [it] returns a singleton list, containing a value of type a that was read from the input string and the remaining string that follows what was parsed. If no parse was possible, however, the result is the empty list, and if there is more than one possible parse (an ambiguity), the resulting list contains more than one pair. Of course we can have other non safe functions, but that is the idea, it is more about a culture of usage than an impossibility to be done. @Fran

I was referring to reads that “Normally, [] [it] returns a singleton list, containing a value of type a that was read from the input string and the remaining string that follows what was parsed. If no parse was possible, however, the result is the empty list, and if there is more than one possible parse (an ambiguity), the resulting list contains more than one pair.

Of course we can have other non safe functions, but that is the idea, it is more about a culture of usage than an impossibility to be done.

]]> By: Fran http://sadekdrobi.com/2008/11/02/code-safety-and-correctness-is-a-matter-of-mindset-cultured-by-the-language/comment-page-1/#comment-5590 Fran Tue, 04 Nov 2008 20:44:57 +0000 http://sadekdrobi.com/2008/11/02/code-safety-and-correctness-is-a-matter-of-mindset-cultured-by-the-language/#comment-5590 But read has exactly the problem discussed here: it will throw an exception if the parser fails. Try read "twenty"::Int But read has exactly the problem discussed here: it will throw an exception if the parser fails.

Try read “twenty”::Int

]]> By: Jam http://sadekdrobi.com/2008/11/02/code-safety-and-correctness-is-a-matter-of-mindset-cultured-by-the-language/comment-page-1/#comment-5573 Jam Sun, 02 Nov 2008 23:51:52 +0000 http://sadekdrobi.com/2008/11/02/code-safety-and-correctness-is-a-matter-of-mindset-cultured-by-the-language/#comment-5573 The function you're looking for is called 'read'. It has type String -> a and is overloaded on the return type. Works for ints, floats, lists etc. The function you’re looking for is called ‘read’. It has type String -> a and is overloaded on the return type. Works for ints, floats, lists etc.

]]> By: Sebastian http://sadekdrobi.com/2008/11/02/code-safety-and-correctness-is-a-matter-of-mindset-cultured-by-the-language/comment-page-1/#comment-5571 Sebastian Sun, 02 Nov 2008 23:03:07 +0000 http://sadekdrobi.com/2008/11/02/code-safety-and-correctness-is-a-matter-of-mindset-cultured-by-the-language/#comment-5571 You have a point, but it's not the best example. The following function is a "simple" string->int conversion (actually, not just int). read :: (Read a) => String -> a You have a point, but it’s not the best example.
The following function is a “simple” string->int conversion (actually, not just int).
read :: (Read a) => String -> a

]]>