Supports plain old arithmetic, bitwise, Python's mathematical functions, and your usual stack operators. Not intended to be Turing-complete!

Originally intended to be a more powerful dc, which lacked many mathematical functions. Is not a superset of dc's feature set though. It notably lacks macros.

• Wanted one in Python.
• rpn has a limited feature set.
• Didn't know about lerpn.
• pyrpn is woefully incomplete.
• Disagreed with RPyN implementation; limited feature set.
• hcpy is missing a few things, and I don't agree with the grammar; shorthand should trump the convenience of the lesser used unquoted function names.
• pycalculator's a GUI. I don't intend on requiring people to have Qt installed, much less look nice, and there is no need for a GUI anyway, at this time.
• rpncalc depends on an external numerical library, and one that you're not likely to already have.
• stacky is a full blown language, and seems abandoned.
• pyrpncalc has excessive printing, I don't agree with the code, and lacks a few features I want.

Just pip install --user https://github.com/pilona/rpn.git.

Example:

$ rpn
> 2 3 + 4 * p
20.0
> 5 f
5.0
20.0
> / 3 % p
1.0
> c
> f
>

List available functions and operators:

> h
functions: abs acos acosh asin asinh atan atan2 atanh ceil copysign cos cosh degrees e erf erfc exp expm1 fabs factorial floor fmod frexp fsum gamma gcd hypot inf isclose isfinite isinf isnan ldexp lgamma log log10 log1p log2 modf nan phase pi polar pow radians rect sin sinh sqrt tan tanh trunc
operators: ! % * + - / = A H I K O P R ^ _ a c d f h i j k l o p r s v x ~ « ° » ∞
formats: D F b c d f i s t

List in long form:

> V
functions:
abs: Return the absolute value of the argument.
acos: acos(x)
acosh: acosh(x)
[…]

operators:
!: not_(a) -- Same as not a.
%: mod(a, b) -- Same as a % b.
*: mul(a, b) -- Same as a * b.
[…]
K: Push output rounding to top of stack.
O: Push output format function to top of stack.
[…]
v: sqrt(x)
~: invert(a) -- Same as ~a.

formats:
D: Decimal
F: Fraction
[…]

Call Python help on a particular operator:

> \%H
Help on function mod in module __main__:

mod(left, right)
    mod(a, b) -- Same as a % b.

Push π, take the sine of it.

> 'pi'$
> 'sin'$
> p
1.2246467991473532e-16

Oops. It's floating point. Let's round to 10 decimal digits.

> 10k
> p
0.0

Play with negative numbers. There is not syntactical support for prefix unary minus. It's done using the unary minus (postfix) operator.

> 1_ 1 +

• No tests at the moment
• Interface subject to change at any moment; ruthlessly clean up or refactor rather than keep bad design around.

• TUI mode (e.g., with curses) or immediate input mode (CBREAK + echo)
  • Would ideally preserve output on exit
• Proper name for PyPI