rulc

cargo: cargo install rulc

• rulc for REPL mode
• rulc --tui, rulc -t for TUI mode
• rulc --exec <expression>, rulc -e <expression> for inline mode
• rulc --help, rulc -h to print usage
• <cmd> | rulc to pipe expressions in (see Piping)

In TUI mode, both Esc and Ctrl+C quit the app.

• rulc --help / rulc -h prints CLI usage (available modes and flags) and exits.
• The help keyword, entered in REPL or TUI mode (or via rulc -e help), prints usage examples along with the list of built-in functions and constants.

Assign a variable:

x = 5
y = x * 2 + 1

Compound assignment:

x += 10
x *= 2

Define a custom function:

f(x) = x^2 + 2*x + 1
g(x) = sin(x) / x

Plots are available in TUI mode (rulc --tui).

Syntax:

draw <function> from <expr> to <expr> | draw <function> (with default domain of definition: [-3; 3])

Examples:

Plot a built-in function:

draw sin from -pi to pi

Define and plot a custom function:

f(x) = x^2 - 4
draw f from -5 to 5

Plot using a computed range:

draw cos from -2*pi to 2*pi

After entering a draw command the chart panel updates automatically. The x and y axes scale to fit the plotted range, and the zero axes are shown in gray when they fall within the visible area.

Multiple draw commands layer their curves on the same chart, each in its own color (up to 5 plots at once; further draw commands are rejected until you clear plots). Points where a function is undefined (e.g. division by zero) are skipped instead of aborting the plot, and statistical outliers near an asymptote are filtered out so a single blown-up sample doesn't stretch the whole chart.

Syntax:

intersect <function> <function> from <expr> to <expr> | intersect <function_1> <function_2> (with default domain of definition: [-3; 3])

Example:

f(x) = x^2
g(x) = x + 2
intersect f g from -5 to 5

Both functions are sampled over the given range and checked for sign changes in their difference; the crossing is then linearly interpolated between samples for a more precise (x, y). In REPL mode the found points are printed one per line. In TUI mode they're additionally marked on the chart and labeled (x, y) in the plot's legend.

Clearing an unknown name reports unknown variable for clear: '<name>', usage: clear <history|memory|plots|<name>>. Builtins (sin, pi, etc.) can't be cleared.

If stdin isn't a terminal, rulc reads expressions from it instead of opening the REPL — no flag needed:

$ echo "2 + 2" | rulc
4
$ printf "x = 5\nx * 2\n" | rulc
x = 5
10

Each line is evaluated on its own; results are printed bare (no >> prefix or color) so they're easy to consume in scripts. Errors go to stderr and processing continues with the next line; if any line failed, rulc exits with a non-zero status.

├── core
└── ├── evaluator           // evaluates parsed expressions
└── ├── lexer               // tokenizes input
└── ├── operations          // defines arithmetic operations
└── ├── parser              // parses tokenized input
└── ├── ├── numeric         // parses numeric expressions
└── ├── registries          // registries for identifiers and operation 
└── view                    // program modes (inline, REPL, TUI, pipe) 
└── main.rs                 // program entry point

1. Tokenize the input using the lexer
2. Parse the tokenized input using the parser
3. Evaluate the parsed expression using the evaluator (Pratt expression parser)

Licensed under the GNU General Public License v3.0 or later (GPL-3.0-or-later). See LICENSE for the full text.