rand works for doubles

Author: erkkikeranen

src/environment.rs

@@ -74,6 +74,7 @@ impl Environment {
         let subtract_fn = rust_core::SubtractFn {};
         let multiply_fn = rust_core::MultiplyFn {};
         let divide_fn = rust_core::DivideFn {};
+        let rand_fn = rust_core::RandFn {};
         let str_fn = rust_core::StrFn {};
         let do_fn = rust_core::DoFn {};
         let nth_fn = rust_core::NthFn {};
@@ -105,6 +106,7 @@ impl Environment {
         environment.insert(Symbol::intern("-"), subtract_fn.to_rc_value());
         environment.insert(Symbol::intern("*"), multiply_fn.to_rc_value());
         environment.insert(Symbol::intern("_slash_"), divide_fn.to_rc_value());
+        environment.insert(Symbol::intern("rand"), rand_fn.to_rc_value());
         environment.insert(Symbol::intern("let"), let_macro.to_rc_value());
         environment.insert(Symbol::intern("str"), str_fn.to_rc_value());
         environment.insert(Symbol::intern("quote"), quote_macro.to_rc_value());

src/rust_core.rs

@@ -22,6 +22,10 @@ pub use self::_divide_::*;
 pub(crate) mod _multiply_;
 pub use self::_multiply_::*;
 
+pub(crate) mod rand;
+pub use self::rand::*;
+
+
 // string
 pub(crate) mod str;
 pub use self::str::*;

src/rust_core/rand.rs

@@ -0,0 +1,35 @@
+use crate::ifn::IFn;
+use crate::value::{Value, ToValue};
+use std::rc::Rc;
+use rand::{random, thread_rng, Rng};
+use crate::error_message;
+use std::any::Any;
+
+/// (rand) or (rand n)
+///
+#[derive(Debug, Clone)]
+pub struct RandFn {}
+impl ToValue for RandFn {
+    fn to_value(&self) -> Value {
+        Value::IFn(Rc::new(self.clone()))
+    }
+}
+impl IFn for RandFn {
+    fn invoke(&self, args: Vec<Rc<Value>>) -> Value {
+        match args.len() {
+            0 => Value::F64(thread_rng().gen()),
+            1 => {
+                let arg = args.get(0).unwrap().to_value();
+                match arg {
+                    Value::I32(i_) => Value::F64(thread_rng().gen_range(0.0, i_ as f64)),
+                    Value::F64(f_) => Value::F64(thread_rng().gen_range(0.0, f_)),
+                    _ => Value::Condition(format!( // TODO: what error message should be returned regarding using typetags?
+                                               "Type mismatch; Expecting: (i32 | i64 | f32 | f64), Found: {}",
+                                               arg.type_tag()
+                ))
+                }
+            },
+            _ => error_message::wrong_varg_count(&[0, 1], args.len())
+        }
+    }
+}