I ask because I'm trying to figure out how to implement pieces with non-displacement capture. Is it possible for a function to relocate a piece after it captures?
The pawn functions use remove to handle en passant capture. This is the only built-in function that normally has an effect, since functions and expressions are normally just supposed to return values. To achieve any other effect in a function, you can call a subroutine from it, and the subroutine can cause any effects you like. But if your interest is in non-displacement capture, then remove should be all you need. See the Breaking Logic section of the fairychess include file tutorial for details on how it is used in the pawn functions.
The pawn functions use remove to handle en passant capture. This is the only built-in function that normally has an effect, since functions and expressions are normally just supposed to return values. To achieve any other effect in a function, you can call a subroutine from it, and the subroutine can cause any effects you like. But if your interest is in non-displacement capture, then
removeshould be all you need. See the Breaking Logic section of the fairychess include file tutorial for details on how it is used in the pawn functions.