Whitespace is an imperative, stack-based language whose only significant characters are space, tab, and linefeed. Operations consists of an instruction type followed by the command. The interpreter maintains a stack of integers and a heap.
Besides the execution of Whitespace programs, this application also supports execution of, and conversion between, a textual format that makes it easier to understand what the program is doing.
For example, pushing a value of 5 onto the stack in Whitespace is coded as SSSTSTL, where S, T, and L represent a space, tab, and linefeed, respectively. This can be seen by the following:
1> W = mrwhite_from_text:convert("stack push 5", return).
" \t \t\n"
2> mrwhite_from_whitespace:convert(W, return).
"stack push 5\n"
The canonical example at the Whitespace page mentioned above, which can be found in priv/sample/canonical.ws and priv/sample/canonical.wst, illustrates a number of the operations supported by the language, and can be run as follows.
3> mrwhite_from_whitespace:run({file_in, "priv/sample/canonical.ws"}).
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ok
$ make will run the lexing and parsing steps, move the generated Erlang modules to src/, compile, and run Eunit tests.
Mr. White was presented in a lightning talk at Erlang & Elixir Factory SF Bay Area 2017 (slides) (video)