ts/README.md

ts

The ts package makes it easy for users to write functions that can be used in rserve-ts applications.

Installation

You can install the development version of ts from GitHub with:

# install.packages("devtools")
devtools::install_github("tmelliott/ts")

Example

Writing functions is easy, just use the ts_*() functions to define formals and return types.

library(ts)
app <- ts_app(
  add = ts_fun(
    function(x, y) {
      x + y
    },
    x = ts_number(),
    y = ts_number(),
    # ideally this will use a generic type where x OR y can be vectors
    # and, if one is a vector, the return type will be a vector too...
    result = ts_number()
  ),
  sample = ts_fun(
    function(x, n) {
      sample(x, n)
    },
    x = ts_character_vector(),
    n = ts_integer(),
    result = ts_condition(n,
      1 = ts_character(),
      ts_character_vector()
    )
  )
)

ts_compile(app)

This will generate the following rserve-ts function definitions:

import { types as R } from "rserve-ts";

export const app = {
  add: z.function(
    z.tuple([z.number(), z.number()]),
    z.promise(R.numeric(1))
  ),
  sample: z.function(
    z.tuple([z.character_vector(), z.integer()]),
    z.promise(R.character())
  )
};

which will generate the following types:

type App = {
  add: (x: number, y: number) => Promise<{ data: number }>;
  sample: (x: string[], n: number) => Promise<{ data: string | string[] }>;
  // or, if possible, even better:
  sample: <N extends number>(x: string[], n: N) =>
    Promise<{ data: N extends 1 ? string : string[] }>;
};

State of the project

Here’s what’s currently working:

library(ts)

myfun <- ts_function(mean, x = ts_numeric(), result = ts_numeric(1))
myfun(1:5)
#> [1] 3

myfun("hello world")
#> Error: Expected a number

cat(readLines("tests/testthat/app/app.R"), sep = "\n")
#> library(ts)
#> 
#> fn_mean <- ts_function(mean, x = ts_numeric(), result = ts_numeric(1))
#> fn_first <- ts_function(function(x) x[1],
#>     x = ts_character(-1), result = ts_character(1)
#> )

ts_compile("tests/testthat/app/app.R", file = "")
#> import type { Character, Numeric } from 'rserve-ts';
#> 
#> const fn_first = (x: string | string[]) => Promise<Character<1>)>;
#> const fn_mean = (x: number | number[]) => Promise<Numeric<1>)>;