On Monday, 12 January 2015 at 00:51:25 UTC, Walter Bright wrote:
On 1/11/2015 5:06 AM, Dicebot wrote:
What is your opinion of approach advertised by various
functional languages and
now also Rust? Where you return error code packed with actual
data and can't
access data without visiting error code too, compiler simply
won't allow it.
It's a great question. I have a lot of experience with error
codes, and with exceptions. I have zero with the packed scheme,
though that doesn't stop me from having an opinion :-)
Perhaps I misunderstand, but given A calls B calls C,
A => B => C
The general solution in functional programming is error chaining.
An example, C is a function that reads in lines of a program and
B is a function that takes all those lines and counts words.
C will either return an error or lines and B will either
immediately return that error to A or convert the lines to word
counts.
This works especially well with function chaining, because you
can hide the error propagation in a generic chaining method
(called map).
http://danielwestheide.com/blog/2012/12/26/the-neophytes-guide-to-scala-part-6-error-handling-with-try.html
