module python
imports libstrategolib signatures/-

signature
  constructors
    TopLevel: Ex -> Ex

rules
  py: TopLevel(x) -> $[import sys
  class StdioC:
    def receives(self, v):
      print(v, file=sys.stdout, end='')
      return self
  Stdio = StdioC()
  [<py>x]]

  py: Stdio() -> $[Stdio]
  py: Int(x) -> x
  py: Sum(x) -> $[sum([<py>x])]
  py: Receives(x, y) -> $[[<py>x].receives([<py>y])]
  py: [] -> $<[]>
  py: [x | xs] -> $<[<<py>x><<pytail>xs>]>

strategies
  // wrap expression in a toplevel and then apply code generation
  python = !TopLevel(<id>); py

  // translate each element of a list, prepending each with ',', and concatenate
  pytail = foldr(!"", \ (x,y) -> $[, [<py>x][y]] \)

  // Interface python code generation with editor services and file system
  to-python: (selected, _, _, path, project-path) -> (filename, result)
    with filename := <guarantee-extension(|"py")> path
       ; result   := <python> selected