Greg

Greg is a tiny Go-based interpreter for a very small, experimental language. This project is still evolving, so the syntax below reflects the currently working implementation rather than a formal language specification.

Requirements

• Go 1.27.1 or later

Running

You can execute a source file directly:

go run . path/to/program.hs

Use -v to print the source, tokens, and current variable values before the program runs:

go run . -v path/to/program.hs

You can also build a standalone binary:

go build -o greg .
./greg path/to/program.hs

Current language features

The parser currently supports:

• typed declarations: i^, f^, and s^
• numeric expressions with +, -, *, and /
• comparisons with > and <
• ++ and -- increment/decrement operators
• if / else blocks with braces
• for (init; condition; update) { ... } loops
• printf("format", args...) output

Examples

Declare and print variables:

i^count = 2
f^ratio = 3.5
s^message = "hello"

printf("%v %v %v\n", count, ratio, message)

This prints:

2 3.5 hello

Conditional logic:

i^count = 2

if count > 1 {
    printf("large\n")
} else {
    printf("small\n")
}

This prints:

large

For loops:

for (i^i = 0; i < 10; i++) {
    printf("%v ", i)
}

This prints:

0 1 2 3 4 5 6 7 8 9 

Important caveat

This interpreter is intentionally minimal and not fully general-purpose. In the current implementation, simple reassignment such as count = count + 1 is not handled by the parser; use declaration syntax plus ++ / -- for updates.

The example programs in the repository are under test/ and are the best reference for the current syntax and behavior.

Note: this README was drafted with AI because I have a life.