On Sat, Jun 30, 2018 at 11:30 AM, Waldek Hebisch
<[email protected]> wrote:
> Bill Page wrote:
>> >
>> > Well, advantage is consistency with rules.
>> >
>>
>> Could you site specifically what rule is being violated?
>
> The one that Ricardo was asking about: that 'if' always works,
> but for one armed 'if' you get Void as a type.
>
>> ...
>> In fact the Spad compiler does not always do what I had hoped. For
>> example compiling the following function using Spad:
>>
>> f(x:Integer):PositiveInteger == if x<1 then 1
>>
>> --
>>
>> (1) -> f(0)
>>
>> (1) 1
>> Type: PositiveInteger
>> (2) -> f(1)
>> Internal Error
>> Interpreter code generation failed for expression(|f| 1)
>
> The message looks fishy. Do you really used _Spad_ function here?
Yes, here is the exact code that I compiled:
-- file: one-armed.spad
)abbrev domain TEST Test
Test(): with
test1: ()->Integer
test2: ()->Void
f:Integer -> PositiveInteger
g:Integer -> PositiveInteger
h:Integer -> PositiveInteger
== add
z:Integer := 1
test1() ==
A := if z<2 then 1
return A
test2() ==
B := if 2<1 then 1
return B
f(x:Integer):PositiveInteger == if x<1 then 1
g(x:Integer):PositiveInteger == coerce((if x<1 then 1 else
void()$Void)::Union(Void,PositiveInteger))
h(x:Integer):PositiveInteger == g(x)+1
--
This is the result:
(1) -> )co one-armed
Compiling FriCAS source code from file /home/wspage/one-armed.spad
using old system compiler.
TEST abbreviates domain Test
...
Test is now explicitly exposed in frame frame1
Test will be automatically loaded when needed from
/home/wspage/TEST.NRLIB/TEST
(1) -> f(0)
(1) 1
Type: PositiveInteger
(2) -> f(1)
Internal Error
Interpreter code generation failed for expression(|f| 1)
(2) -> g(0)
(2) 1
Type: PositiveInteger
(3) -> g(1)
>> Error detected within library code:
"()" of mode Union(Void,PositiveInteger) cannot be coerced to mode
PositiveInteger
(3) -> h(0)
(3) 2
Type: PositiveInteger
(4) -> h(1)
>> Error detected within library code:
"()" of mode Union(Void,PositiveInteger) cannot be coerced to mode
PositiveInteger
(4) ->
> The message looks like coming from interpreter and given
> Spad function of correct type interpreter should just blindly
> call it.
>
Yes, I thought so too.
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