Hello: I would like to implement a new "calling convention" for Maple language, so that programers in Haskell may call for Maple routines. Both languages are intereseting for cooperation, due to its symbolic expresiveness. Maple 9.3 has released "Open Maple", somewhat like JNI for Java, if I'm not wrong. So a good start point to conider how to marshall these environments... I'm a newbie on FFI. Help required specilly from those working on Java FFI. Sorry for the obscure points. 1.- My initial schema is: C --------> Java Haskell --------> Maple A C programmer invokes the Java Virtual Machine as a Haskell programmer will invoke the Maple "kernel" handle (MKV). ( Strictly speaking, this should be done by the "calling convention" mechanism in a trasnparent way, since the final user has only to program the maple routines and to use the mandatory declarations: foreign import c e v :: t foreign export c e v :: t file a.maple: ------------- proc e(a,b) return a+b; end; ) 2.- The JVM initializes on a ".class" file, i.e, byte-code, as MKV straightly on source language ".maple" . 3.- What a "calling convention" must implement ? How to implement it ? I mean, JNI exports marshalling/unarshalling of types from Java to C, and access to attrbiutes/ invokes of methods of a given object on Java.. In time, Open Maple exports marshalling/unmarshalling of types between Maple AND C, and several ways of invoke the maple-kernel. So I should implement Maple and Haskell marshalling -via C , right ? I should implement the "maple" convention by using the "ccall" convention. So, there is a sort of "template" to implement a "calling convention"? This is a obscure point for me... 4.- What about side effects ? I mean, invoking a function on Maple may change the state of interpreter, and further calls may diff. Should I pass to the final user a handle to the KVM , or create a new type of monad, like... type MapleMonad a = stateKVM-> (stateKVM,val) instance Monad MapleMonad a ... >>= >> ..