isitoq

This language was an entry to the January 2013 PLTGames Competition.

The following is from the readme on github:

Overview

From Wikipedia:

In Inuit mythology, Issitoq (also Isitoq) is a deity that punishes 
those who break taboos. He usually takes the form of a giant flying 
eye.

Isitoq is a programming language centered around the idea of testing.
It is extremely minimal, consisting of a single datatype (boolean values),and a few operations which revolve around comparing values. It has a single vital operation, ? (the test operation) which is universal and functionally complete, as it can implement a simple NOR gate.

Isitoq will berate users for breaking programs, or for writing assertions that fail. However, it won't necessarily be easy to figure out whatyou did wrong.

How Isitoq Works

Isitoq programs work on a single main stack, with new stacks definedon the fly for each function call, to prevent value leakage.

When calling a function, it pops the correct number of arguments off of the stack, pushes them in the correct order onto a new stack, and thenoperates on that new stack. After function execution, the function stack is destroyed.

Aside from function calls, there are two literal value words that simply push values to the stack, t and f, which represent true and false, respectively.

There are also two operators which work similarly. The main operator is the ? (test) operator, which needs at least one comparison valueto check the value(s) at the top of the stack against. If they match, a t is pushed to the stack, else a f is pushed to the stack.

The last operator is the ! (assert) operator. ! operates similarly to ?, except that it does not push a value to the stack. Instead, it will halt your program and make Ishitoq angry if it's values do not match the top of the stack. Otherwise, the program continues along silently.

Both ? and ! check the values on top of their current stack (function or main), but ? pushes it's results to the parent stack. This is howvalues are returned from functions.

As you may have gleaned, the only way to pop values from the stack is by calling a function, and the main way of getting anything accomplished isby using the ? operator. This system is functionally complete by virtue of the fact that NOR can be defined like so:

// define the `nor` function
:nor .. -> ?f|f
// :nor = define a function named nor
// ..   = that takes two parameters
// ->   = and has a body that specifies...
// ?f|f = if the top two values of the current stack 
//        (the function stack) are `f`, push a `t` to
//        the calling stack

From this, we can define all of the other logic gates:

:id .    -> ?t ?t // duplicate the top item on the calling stack
:not .   -> id nor ?t
:and ..  -> ?t|t
:nand .. -> and not ?t
:or ..   -> nor not ?t
:xor ..  -> or . .. nand and ?t
:xnor .. -> xor not ?t

I wouldn't call Isitoq Turing complete, but you can accomplish a lot with these fundamental building blocks.

Example Program

// define some functions
:id .    -> ?t ?t
:nor ..  -> ?f|f
:not .   -> id nor ?t
:and ..  -> ?t|t
:nand .. -> and not ?t
:or ..   -> nor not ?t
:xor ..  -> or . .. nand and ?t
:xnor .. -> xor not ?t

// do some things
t id !t|t   // push t to the stack, duplicate, and assert that 
            // top of stack is [t, t]<=
id !t|t|t   // duplicate top of stack, assert that top of stack is [t, t, t]<=
nor !f      // nor the top two items, and assert that top of stack is f
nor !f      // same
id nor !t   // dup, nor, assert t
not !f      // negate, assert f
t nand !t   // push t, nand, assert t
f !f|t      // push f, assert top of stack is [t, f]<=
?t|f !f|f|t // test if top of stack is [f, t]<=, assert [t, f, f]<=

The output of this program is as follows:

$ python isitoq.py test.isq
ISITOQ has contemplated your input, and determined the following:
[t, f, f]<==
BE HAPPY, MORTAL, THAT YOUR PROGRAM RAN WITHOUT FLAWS.

With debugging, it's like this:

$ python isitoq.py -d test.isq
STACK BEFORE WORD t: []<==
STACK BEFORE WORD id: [t]<==
  STACK BEFORE WORD ?t: [t]<==
  STACK BEFORE WORD ?t: [t]<==
STACK BEFORE WORD !t|t: [t, t]<==
STACK BEFORE WORD id: [t, t]<==
  STACK BEFORE WORD ?t: [t]<==
  STACK BEFORE WORD ?t: [t]<==
STACK BEFORE WORD !t|t|t: [t, t, t]<==
STACK BEFORE WORD nor: [t, t, t]<==
  STACK BEFORE WORD ?f|f: [t, t]<==
STACK BEFORE WORD !f: [t, f]<==
STACK BEFORE WORD nor: [t, f]<==
  STACK BEFORE WORD ?f|f: [t, f]<==
STACK BEFORE WORD !f: [f]<==
STACK BEFORE WORD id: [f]<==
  STACK BEFORE WORD ?t: [f]<==
  STACK BEFORE WORD ?t: [f]<==
STACK BEFORE WORD nor: [f, f]<==
  STACK BEFORE WORD ?f|f: [f, f]<==
STACK BEFORE WORD !t: [t]<==
STACK BEFORE WORD not: [t]<==
  STACK BEFORE WORD id: [t]<==
    STACK BEFORE WORD ?t: [t]<==
    STACK BEFORE WORD ?t: [t]<==
  STACK BEFORE WORD nor: [t, t]<==
    STACK BEFORE WORD ?f|f: [t, t]<==
  STACK BEFORE WORD ?t: [f]<==
STACK BEFORE WORD !f: [f]<==
STACK BEFORE WORD t: [f]<==
STACK BEFORE WORD nand: [f, t]<==
  STACK BEFORE WORD and: [f, t]<==
    STACK BEFORE WORD ?t|t: [f, t]<==
  STACK BEFORE WORD not: [f]<==
    STACK BEFORE WORD id: [f]<==
      STACK BEFORE WORD ?t: [f]<==
      STACK BEFORE WORD ?t: [f]<==
    STACK BEFORE WORD nor: [f, f]<==
      STACK BEFORE WORD ?f|f: [f, f]<==
    STACK BEFORE WORD ?t: [t]<==
  STACK BEFORE WORD ?t: [t]<==
STACK BEFORE WORD !t: [t]<==
STACK BEFORE WORD f: [t]<==
STACK BEFORE WORD !f|t: [t, f]<==
STACK BEFORE WORD ?t|f: [t, f]<==
STACK BEFORE WORD !f|f|t: [t, f, f]<==
ISITOQ has contemplated your input, and determined the following:
[t, f, f]<==
BE HAPPY, MORTAL, THAT YOUR PROGRAM RAN WITHOUT FLAWS.

Happy Hacking!

Get it

You can get isitoq at its official github repo: gatesphere/isitoq