Module and .mli files

Learning
1

Hi,

I am building a library, with a .mli file. The signature of one the function requires a StringMap (Map of Strings) produced with :

module StringMap = Map.Make (String)

Dune does not like this line and says :

Syntax error

showing the first parenthesis

What is wrong with this ?

2

It needs to be a module type:

module StringMap : Map.S with type elt = string
3

Thanks, indeed it makes sense to have types in .mli file.

It should be with type key = string rather than elt…

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4

FYI your first try was not that far as this can also be written module StringMap : module type of Map.Make(String)

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