Module type Args

argument lists and associated N-ary map and apply functions

Signature

type 'a arg

the underlying applicative

type ('f, 'r) t

'f is the type of a function that consumes the list of arguments and returns an 'r.

val nil : ('r, 'r) t

the empty argument list *

val cons : 'a arg -> ('f, 'r) t -> ('a -> 'f, 'r) t

prepend an argument

val (@>) : 'a arg -> ('f, 'r) t -> ('a -> 'f, 'r) t

infix operator for cons

val step : ('f1, 'r) t -> f:('f2 -> 'f1) -> ('f2, 'r) t

Transform argument values in some way. For example, one can label a function argument like so:


        step ~f:(fun f x -> f ~foo:x) : ('a -> 'r1, 'r2) t -> (foo:'a -> 'r1, 'r2) t

The preferred way to factor out an Args sub-sequence:


        let args =
          Foo.Args.(
            bar "A"
            (* TODO: factor out the common baz qux sub-sequence *)
            @> baz "B"
            @> qux "C"
            @> zap "D"
            @> nil
          )

is to write a function that prepends the sub-sequence:


        let baz_qux remaining_args =
          Foo.Args.(
            baz "B"
            @> qux "C"
            @> remaining_args
          )

and splice it back into the original sequence using @@ so that things line up nicely:


        let args =
          Foo.Args.(
            bar "A"
            @> baz_qux
            @@ zap "D"
            @> nil
          )

val mapN : f:'f -> ('f, 'r) t -> 'r arg

val applyN : 'f arg -> ('f, 'r) t -> 'r arg