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main.ml
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open Core
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Other files (modules) will be able to use another module's code by referring to its filename with an uppercase.
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let () =
let two = Add.add_one 1 in
printf "two: %d\n" two
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Modules can also appear within a file.
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module Thing = struct
let add_two i = i + 2
end
let () =
let three = Thing.add_two 1 in
printf "three: %d\n" three
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A module **signature** can also be defined.
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module BiggerThing : sig
val add_three : int -> int
end = struct
let add_three i = i + 3
end
let () =
let four = BiggerThing.add_three 1 in
printf "four: %d\n" four
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A module can also re-use other modules by either **including** a whole module or re-using parts of a module.
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module WrappingThing : sig
val add_one : int -> int
val add_three : int -> int
val add_four : int -> int
end = struct
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by either **including** a whole module or re-using parts of a module.
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include Add
let add_three = BiggerThing.add_three
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or re-using parts of a module.
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open BiggerThing
let add_four i = add_one @@ add_three @@ i
end
let () =
let five = WrappingThing.add_four 1 in
printf "five: %d\n" five
module Nested = struct
module NestedNested = struct
let add_five i = i + 5
end
let add_six i = 1 + NestedNested.add_five i
end
let () =
let six = Nested.NestedNested.add_five 1 in
let seven = Nested.add_six 1 in
printf "six: %d\n" six;
printf "seven: %d\n" seven;
module type SomeSignature = sig
val i : int
end
module SomeModule1 : SomeSignature = struct
let i = 1
end
module SomeModule2 = struct let i = 2 end
let () =
let instance1 = (module SomeModule1 : SomeSignature) in
let modules = [ instance1 ; (module SomeModule2) ] in
let modules = modules @ [(module struct let i = 3 end)] in
let module NNN = (val instance1 : SomeSignature) in
let instance2 = match List.last modules with Some x -> x | None -> failwith "impossible" in
let module VVV = (val instance2 : SomeSignature) in
printf "%d - %d\n" NNN.i VVV.i
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