Consider the two following code snippets type atp type smt type _ config = | ConfigSmt : smt config | ConfigAtp : atp config let digest : smt config -> unit = fun cfg -> match cfg with ConfigSmt -> () and module M = struct type atp type smt type _ config = | ConfigSmt : smt confi…

This is because atp and smt have no representation outside the current module, so the compiler cannot deduce that they are different. One trick is to give them a form in the : type atp = Atp type smt = Smt

Generalised abstract data types, phantom types and modules

Learning

koizel February 28, 2024, 10:47am 3

My bad, this is a duplicate of Unable to refute impossible GADT pattern when phantom types belong to a module

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Generalised abstract data types, phantom types and modules

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