README.md

rhcalc

rhcalc is a Reverse Polish Notation (RPN) calculator written in Haskell.

Usage

Run cabal install to build, then rhcalc.

Features

rhcalc performs exact computations on integers and fractions. The division of two integers is a fraction, not a decimal number.

Basic operations: + - * / ^, inverse (inv), negative (n), absolute value (abs), conversion from exact to decimal (num), rounding (rnd, floor, ceil).

Math functions: trigonometry (cos, sin, tan, angles in radians), exp, log, sqrt.

Logic operations (booleans) (not, and, or, xor, nand, nor) and tests (==, <, >, /=, <=, >=).

• 5 8 == -> False
• True False xor -> True

Unit conversions: some common length, volume, weight, and temperature units are included. rhcalc favors exact conversions using fractions most of the time. Input: [value] [unit from] [unit to] convert

• 1 mile yd convert -> 1760
• 12 inch foot convert -> 1
• 1 gal l convert -> 59148/15625
• 1 gal l convert num -> 3.785472
• 212 dF dC convert -> 100.0[...]

Lists: rhcalc handles heterogenous lists and provides basic operations on them.

• 2 3 4 [] : : : -> [2,3,4]
• [2,3] 4 : -> [4,2,3]
• 4 [2,3] : -> [4,2,3]
• 1 5 range 6 8 range ++ -> [1,2,3,4,5,6,7,8]
• [1,2,3,4,5,6,7,8] 3 drop -> [4,5,6,7,8]
• [4,5,6,7,8] 2 take -> [4,5]
• [4,5,6,7,8] init -> [4,5,6,7]
• [4,5,6,7] tail -> [5,6,7]
• [5,6,7] reverse -> [7,6,5]

Stack operations

• swap exchanges the two elements at the top of the stack.

% 8 str
2: 8
1: str
% swap
2: str
1: 8

• del removes the top element from the stack.

2: str
1: 8
% del
1: str

• dup duplicates the first element on the stack.

1: str
% dup
2: str
1: str

• rep repeats the second element on the stack by the first. example: 5 8 rep removes 5 and 2 from the stack and puts back eight times 5.

% 5
1: 5
% 8 rep
(4 more on the stack)
4: 5
3: 5
2: 5
1: 5

• get puts the n-th element on the stack at the top.

3: 5
2: 2.5
1: 8
% 2 get
3: 5
2: 8
1: 2.5
% 3 get
3: 8
2: 2.5
1: 5

• cls clears the stack.

3: 8
2: 2.5
1: 5
% cls

• type puts on the stack the type of the top element.

1: 5
% type
2: 5
1: Integer
% 2.5 type
4: 5
3: Integer
2: 2.5
1: Real

Memory

rhcalc can store values and scripts in memory.

42 answer store stores 42 in the variable answer. When you type answer on the input, 42 is pushed on the stack.

Scripts use the RPN notation and are stored in memory as strings. "5 +" addfive store stores the script 5 + in the variable addfive. Scripts are executed with run: 8 addfive run -> 13

To delete a variable or a script from the memory, type its name between " and clear: "addfive" clear.

You can look at the state of the memory with vars: vars -> [("addfive","5 +"),("answer",42)]

The memory is lost when you exit rhcalc.

"

Settings

rhcalc supports a base setting to display integers on the stack in other bases (hexadecimal, binary, octal, or other bases you fancy).

16 base sets the base to 16 (hexadecimal), and 10 base sets it back to decimal.

The settings command shows the current settings:

% settings
1: Decimal Rad
% 16 base
1: Decimal Rad
% settings
2: Decimal Rad
1: Hex Rad