On Fri, Jun 29, 2018 at 11:22 AM, Waldek Hebisch <hebi...@math.uni.wroc.pl> wrote: > Riccardo GUIDA wrote: >> ... >> 3) The user is puzzled because > > The command line is not representative of FriCAS language.
In my opinion it should be (almost) representative of FriCAS language (SPAD). > On command line interpreter evaluates things so can use actual values > to guess what would be useful. Yes, one should expect that the interpreter would try harder to guess reasonable types in order to relieve the user of (some) of this responsibility. > In the process it breaks several normal rules. > > Try: > > f(x) == if (x > 1) then 1 > Type: Void > Time: 0 sec > (7) -> f(2) > Compiling function f with type PositiveInteger -> Void > Type: Void > Time: 0.02 (OT) = 0.02 sec > (8) -> f(0) > Compiling function f with type NonNegativeInteger -> Void > Type: Void > Time: 0.01 (OT) = 0.01 sec > > In both cases you now get Void. Clearly this is a very poor (though technically correct) guess as to what the user might have wanted. > Unlike Spad compiler trying to declare type does not change the result: > > (9) -> f2(x : Integer) : Integer == if (x > 1) then 1 > Function declaration f2 : Integer -> Integer has been added to > workspace. > Type: Void > Time: 0 sec > (10) -> f2(2) > Compiling function f2 with type Integer -> Integer > Conversion failed in the compiled user function f2 . > > Cannot convert the value from type Void to Integer . > > (10) -> f2(0) > Conversion failed in the compiled user function f2 . > > Cannot convert the value from type Void to Integer . > I cannot see any advantage in having this behavior in the interpreter.I think the interpreter should be changed to do the same thing as the Spad compiler. The function should attempt to coerce the result of the if-then expression if (x > 1) then 1 to Integer. Of course this might cause an error for certain values of x but the user is not likely to be surprised by this. -- You received this message because you are subscribed to the Google Groups "FriCAS - computer algebra system" group. To unsubscribe from this group and stop receiving emails from it, send an email to fricas-devel+unsubscr...@googlegroups.com. To post to this group, send email to fricas-devel@googlegroups.com. Visit this group at https://groups.google.com/group/fricas-devel. For more options, visit https://groups.google.com/d/optout.
