ksl 0.1.30

KSL core library and interpreter
Documentation 
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//! # ksl::builtin::glt
//!
//! Built-in function `Greater` and `Less`.

use crate::{Environment, FALSE_SYMBOL, TRUE_SYMBOL, eval::apply::eval_apply, value::Value};

pub(crate) fn builtin(args: &[Value], is_greater: bool, env: Environment) -> Result<Value, std::sync::Arc<str>> {
    if let [v1, v2] = args {
        match (eval_apply(v1, env.clone())?, eval_apply(v2, env)?) {
            (Value::Number(n1), Value::Number(n2)) => Ok(if if is_greater { n1 > n2 } else { n1 < n2 } {
                TRUE_SYMBOL.clone()
            } else {
                FALSE_SYMBOL.clone()
            }),
            (Value::Number(_), e) => Err(std::sync::Arc::from(format!(
                concat!("Error[ksl::builtin::{}]: ", "Unexpected value: `{}`."),
                if is_greater { "Greater" } else { "Less" },
                e
            ))),
            (e, _) => Err(std::sync::Arc::from(format!(
                concat!("Error[ksl::builtin::{}]: ", "Unexpected value: `{}`."),
                if is_greater { "Greater" } else { "Less" },
                e
            ))),
        }
    } else {
        Err(std::sync::Arc::from(format!(
            concat!(
                "Error[ksl::builtin::{}]: ",
                "Expected 2 parameters, but {} were passed."
            ),
            if is_greater { "Greater" } else { "Less" },
            args.len()
        )))
    }
}