Proposed function: (using ...)

[jarcane]

At the present moment, Heresy lacks I/O routines beyond the simple console IO provided by print and input.

However, we have in our hands already the tools then for some basic file I/O: Racket's print and read routines generally default to a port, and as well there is syntax provided to parameterize just which port those routines point to.

BASIC as well already supplies a very similar approach to I/O: The USING keyword. This is defined in the ECMA standard, as well as many MS-derived BASICs, used to point the output of PRINT to a specific port number (generally mapped to disk and printers and such).

I propose borrowing this as a parameterized block, with syntax to indicate what target or source is to be operated on. Initially, I think file I/O is probably the most useful here, and suggest something like the following:

(using file *filename* as ['write/read]
  ...)

This does beg the question however of whether this violates the functional principle, but remember Rule #3, Heresy is not Haskell. As well, I think limiting this behavior to within explicit 'impure' code-blocks like (using) helps preserve the feel as well, enforcing a certain attention to what is happening whenever such IO is undertaken.

Then again, I may just be mad.

[jarcane]

Implemented for files now.