[Axiom-developer] [#20 D(1, z) fails] wrong arument types

[anonymous]

D(1,z) is not a valid type signature. Try

D(1::Expression(Integer),z) ==> 0


In Axiom it is important to know the type of the arguments to a function.
In this case you gave the D function a PositveInteger and is does not
have a path to coerce PostiveInteger -> Expression(Integer).

Whenever you see the message about exposed and unexposed library functions
the meaning is that you didn't match the type of the arguments and the
interpreter couldn't get there from here. 

The coercion/conversion tower in the interpreter is not well defined
and sometimes it needs help.

Tim

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