pub struct List { /* private fields */ }Expand description
A Lisp list, implemented as a linked-list
Implementations§
source§impl List
impl List
pub const NIL: List = _
sourcepub fn car(&self) -> Result<Value, RuntimeError>
pub fn car(&self) -> Result<Value, RuntimeError>
Examples found in repository?
src/interpreter.rs (line 64)
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fn eval_inner(
env: Rc<RefCell<Env>>,
expression: &Value,
context: Context,
) -> Result<Value, RuntimeError> {
if context.quoting {
match expression {
Value::List(list) if *list != List::NIL => match &list.car()? {
Value::Symbol(Symbol(keyword)) if keyword == "comma" => {
// do nothing, handle it down below
}
_ => {
return list
.into_iter()
.map(|el| eval_inner(env.clone(), &el, context))
.collect::<Result<List, RuntimeError>>()
.map(Value::List);
}
},
_ => return Ok(expression.clone()),
}
}
match expression {
// look up symbol
Value::Symbol(symbol) => env.borrow().get(symbol).ok_or_else(|| RuntimeError {
msg: format!("\"{}\" is not defined", symbol),
}),
// s-expression
Value::List(list) if *list != List::NIL => {
match &list.car()? {
// special forms
Value::Symbol(Symbol(keyword)) if keyword == "comma" => {
eval_inner(env, &list.cdr().car()?, context.quoting(false))
}
Value::Symbol(Symbol(keyword)) if keyword == "quote" => {
eval_inner(env, &list.cdr().car()?, context.quoting(true))
}
Value::Symbol(Symbol(keyword)) if keyword == "define" || keyword == "set" => {
let args = &list.cdr().into_iter().collect::<Vec<Value>>();
let symbol = require_typed_arg::<&Symbol>(keyword, args, 0)?;
let value_expr = require_arg(keyword, args, 1)?;
let value = eval_inner(env.clone(), value_expr, context.found_tail(true))?;
if keyword == "define" {
env.borrow_mut().define(symbol.clone(), value.clone());
} else {
env.borrow_mut().set(symbol.clone(), value.clone())?;
}
Ok(value)
}
Value::Symbol(Symbol(keyword)) if keyword == "defmacro" => {
let args = &list.cdr().into_iter().collect::<Vec<Value>>();
let symbol = require_typed_arg::<&Symbol>(keyword, args, 0)?;
let argnames_list = require_typed_arg::<&List>(keyword, args, 1)?;
let argnames = value_to_argnames(argnames_list.clone())?;
let body = Rc::new(Value::List(list.cdr().cdr().cdr()));
let lambda = Value::Macro(Lambda {
closure: env.clone(),
argnames,
body,
});
env.borrow_mut().define(symbol.clone(), lambda);
Ok(Value::NIL)
}
Value::Symbol(Symbol(keyword)) if keyword == "defun" => {
let args = &list.cdr().into_iter().collect::<Vec<Value>>();
let symbol = require_typed_arg::<&Symbol>(keyword, args, 0)?;
let argnames_list = require_typed_arg::<&List>(keyword, args, 1)?;
let argnames = value_to_argnames(argnames_list.clone())?;
let body = Rc::new(Value::List(list.cdr().cdr().cdr()));
let lambda = Value::Lambda(Lambda {
closure: env.clone(),
argnames,
body,
});
env.borrow_mut().define(symbol.clone(), lambda);
Ok(Value::NIL)
}
Value::Symbol(Symbol(keyword)) if keyword == "lambda" => {
let args = &list.cdr().into_iter().collect::<Vec<Value>>();
let argnames_list = require_typed_arg::<&List>(keyword, args, 0)?;
let argnames = value_to_argnames(argnames_list.clone())?;
let body = Rc::new(Value::List(list.cdr().cdr()));
Ok(Value::Lambda(Lambda {
closure: env,
argnames,
body,
}))
}
Value::Symbol(Symbol(keyword)) if keyword == "let" => {
let let_env = Rc::new(RefCell::new(Env::extend(env)));
let args = &list.cdr().into_iter().collect::<Vec<Value>>();
let declarations = require_typed_arg::<&List>(keyword, args, 0)?;
for decl in declarations.into_iter() {
let decl = &decl;
let decl_cons: &List = decl.try_into().map_err(|_| RuntimeError {
msg: format!("Expected declaration clause, found {}", decl),
})?;
let symbol = &decl_cons.car()?;
let symbol: &Symbol = symbol.try_into().map_err(|_| RuntimeError {
msg: format!("Expected symbol for let declaration, found {}", symbol),
})?;
let expr = &decl_cons.cdr().car()?;
let result = eval_inner(let_env.clone(), expr, context.found_tail(true))?;
let_env.borrow_mut().define(symbol.clone(), result);
}
let body = &Value::List(list.cdr().cdr());
let body: &List = body.try_into().map_err(|_| RuntimeError {
msg: format!(
"Expected expression(s) after let-declarations, found {}",
body
),
})?;
eval_block_inner(let_env, body.into_iter(), context)
}
Value::Symbol(Symbol(keyword)) if keyword == "begin" => {
eval_block_inner(env, list.cdr().into_iter(), context)
}
Value::Symbol(Symbol(keyword)) if keyword == "cond" => {
let clauses = list.cdr();
for clause in clauses.into_iter() {
let clause = &clause;
let clause: &List = clause.try_into().map_err(|_| RuntimeError {
msg: format!("Expected conditional clause, found {}", clause),
})?;
let condition = &clause.car()?;
let then = &clause.cdr().car()?;
if eval_inner(env.clone(), condition, context.found_tail(true))?.into() {
return eval_inner(env, then, context);
}
}
Ok(Value::NIL)
}
Value::Symbol(Symbol(keyword)) if keyword == "if" => {
let args = &list.cdr().into_iter().collect::<Vec<Value>>();
let condition = require_arg(keyword, args, 0)?;
let then_expr = require_arg(keyword, args, 1)?;
let else_expr = require_arg(keyword, args, 2).ok();
if eval_inner(env.clone(), condition, context.found_tail(true))?.into() {
eval_inner(env, then_expr, context)
} else {
else_expr
.map(|expr| eval_inner(env, &expr, context))
.unwrap_or(Ok(Value::NIL))
}
}
Value::Symbol(Symbol(keyword)) if keyword == "and" || keyword == "or" => {
let args = &list.cdr().into_iter().collect::<Vec<Value>>();
let is_or = keyword.as_str() == "or";
let mut last_result: Option<Value> = None;
for arg in args {
let result = eval_inner(env.clone(), arg, context.found_tail(true))?;
let truthy: bool = (&result).into();
if is_or == truthy {
return Ok(result);
}
last_result = Some(result);
}
Ok(if let Some(last_result) = last_result {
last_result
} else {
// there were zero arguments
(!is_or).into()
})
}
// function call or macro expand
_ => {
let mut func_or_macro =
eval_inner(env.clone(), &list.car()?, context.found_tail(true))?;
if matches!(func_or_macro, Value::Macro(_)) {
let args = list.into_iter().skip(1).collect::<Vec<Value>>();
let expanded =
call_function_or_macro(env.clone(), &mut func_or_macro, args)?;
eval_inner(env.clone(), &expanded, Context::new())
} else {
let args = list
.into_iter()
.skip(1)
.map(|car| eval_inner(env.clone(), &car, context.found_tail(true)))
.collect::<Result<Vec<Value>, RuntimeError>>()?;
if !context.found_tail && context.in_func {
Ok(Value::TailCall {
func: Rc::new(func_or_macro),
args,
})
} else {
let mut res =
call_function_or_macro(env.clone(), &mut func_or_macro, args);
while let Ok(Value::TailCall { func, args }) = res {
res = call_function_or_macro(env.clone(), func.as_ref(), args);
}
res
}
}
}
}
}
// plain value
_ => Ok(expression.clone()),
}
}More examples
src/default_environment.rs (line 108)
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pub fn default_env() -> Env {
let mut env = Env::new();
env.define(
Symbol::from("print"),
Value::NativeFunc(|_env, args| {
let expr = require_arg("print", &args, 0)?;
println!("{}", &expr);
Ok(expr.clone())
}),
);
env.define(
Symbol::from("is_null"),
Value::NativeFunc(|_env, args| {
let val = require_arg("is_null", &args, 0)?;
Ok(Value::from(*val == Value::NIL))
}),
);
env.define(
Symbol::from("is_number"),
Value::NativeFunc(|_env, args| {
let val = require_arg("is_number", &args, 0)?;
Ok(match val {
Value::Int(_) => Value::True,
Value::Float(_) => Value::True,
_ => Value::NIL,
})
}),
);
env.define(
Symbol::from("is_symbol"),
Value::NativeFunc(|_env, args| {
let val = require_arg("is_symbol", &args, 0)?;
Ok(match val {
Value::Symbol(_) => Value::True,
_ => Value::NIL,
})
}),
);
env.define(
Symbol::from("is_boolean"),
Value::NativeFunc(|_env, args| {
let val = require_arg("is_boolean", &args, 0)?;
Ok(match val {
Value::True => Value::True,
Value::False => Value::True,
_ => Value::NIL,
})
}),
);
env.define(
Symbol::from("is_procedure"),
Value::NativeFunc(|_env, args| {
let val = require_arg("is_procedure", &args, 0)?;
Ok(match val {
Value::Lambda(_) => Value::True,
Value::NativeFunc(_) => Value::True,
_ => Value::NIL,
})
}),
);
env.define(
Symbol::from("is_pair"),
Value::NativeFunc(|_env, args| {
let val = require_arg("is_pair", &args, 0)?;
Ok(match val {
Value::List(_) => Value::True,
_ => Value::NIL,
})
}),
);
env.define(
Symbol::from("car"),
Value::NativeFunc(|_env, args| {
let list = require_typed_arg::<&List>("car", &args, 0)?;
list.car()
}),
);
env.define(
Symbol::from("cdr"),
Value::NativeFunc(|_env, args| {
let list = require_typed_arg::<&List>("cdr", &args, 0)?;
Ok(Value::List(list.cdr()))
}),
);
env.define(
Symbol::from("cons"),
Value::NativeFunc(|_env, args| {
let car = require_arg("cons", &args, 0)?;
let cdr = require_typed_arg::<&List>("cons", &args, 1)?;
Ok(Value::List(cdr.cons(car.clone())))
}),
);
env.define(
Symbol::from("list"),
Value::NativeFunc(|_env, args| Ok(Value::List(args.iter().collect::<List>()))),
);
env.define(
Symbol::from("nth"),
Value::NativeFunc(|_env, args| {
let index = require_typed_arg::<IntType>("nth", &args, 0)?;
let list = require_typed_arg::<&List>("nth", &args, 1)?;
let index = TryInto::<usize>::try_into(index).map_err(|_| RuntimeError {
msg: "Failed converting to `usize`".to_owned(),
})?;
Ok(list.into_iter().nth(index).unwrap_or(Value::NIL))
}),
);
env.define(
Symbol::from("sort"),
Value::NativeFunc(|_env, args| {
let list = require_typed_arg::<&List>("sort", &args, 0)?;
let mut v: Vec<Value> = list.into_iter().collect();
v.sort();
Ok(Value::List(v.into_iter().collect()))
}),
);
env.define(
Symbol::from("reverse"),
Value::NativeFunc(|_env, args| {
let list = require_typed_arg::<&List>("reverse", &args, 0)?;
let mut v: Vec<Value> = list.into_iter().collect();
v.reverse();
Ok(Value::List(v.into_iter().collect()))
}),
);
env.define(
Symbol::from("map"),
Value::NativeFunc(|env, args| {
let func = require_arg("map", &args, 0)?;
let list = require_typed_arg::<&List>("map", &args, 1)?;
list.into_iter()
.map(|val| {
let expr = lisp! { ({func.clone()} (quote {val})) };
eval(env.clone(), &expr)
})
.collect::<Result<List, RuntimeError>>()
.map(Value::List)
}),
);
// 🦀 Oh the poor `filter`, you must feel really sad being unused.
env.define(
Symbol::from("filter"),
Value::NativeFunc(|env, args| {
let func = require_arg("filter", &args, 0)?;
let list = require_typed_arg::<&List>("filter", &args, 1)?;
list.into_iter()
.filter_map(|val: Value| -> Option<Result<Value, RuntimeError>> {
let expr = lisp! { ({func.clone()} (quote {val.clone()})) };
match eval(env.clone(), &expr) {
Ok(matches) => {
if matches.into() {
Some(Ok(val))
} else {
None
}
}
Err(e) => Some(Err(e)),
}
})
.collect::<Result<List, RuntimeError>>()
.map(Value::List)
}),
);
env.define(
Symbol::from("length"),
Value::NativeFunc(|_env, args| {
let list = require_typed_arg::<&List>("length", &args, 0)?;
cfg_if! {
if #[cfg(feature = "bigint")] {
Ok(Value::Int(list.into_iter().len().into()))
} else {
Ok(Value::Int(list.into_iter().len() as IntType))
}
}
}),
);
env.define(
Symbol::from("range"),
Value::NativeFunc(|_env, args| {
let start = require_typed_arg::<IntType>("range", &args, 0)?;
let end = require_typed_arg::<IntType>("range", &args, 1)?;
let mut current = start;
Ok(Value::List(
std::iter::from_fn(move || {
if current == end {
None
} else {
let res = Some(current.clone());
current += 1;
res
}
})
.map(Value::from)
.collect(),
))
}),
);
env.define(
Symbol::from("hash"),
Value::NativeFunc(|_env, args| {
let chunks = args.chunks(2);
let mut hash = HashMap::new();
for pair in chunks {
let key = pair.get(0).unwrap();
let value = pair.get(1);
if let Some(value) = value {
hash.insert(key.clone(), value.clone());
} else {
return Err(RuntimeError {
msg: format!("Must pass an even number of arguments to 'hash', because they're used as key/value pairs; found extra argument {}", key)
});
}
}
Ok(Value::HashMap(Rc::new(RefCell::new(hash))))
}),
);
env.define(
Symbol::from("hash_get"),
Value::NativeFunc(|_env, args| {
let hash = require_typed_arg::<&HashMapRc>("hash_get", &args, 0)?;
let key = require_arg("hash_get", &args, 1)?;
Ok(hash
.borrow()
.get(key)
.map(|v| v.clone())
.unwrap_or(Value::NIL))
}),
);
env.define(
Symbol::from("hash_set"),
Value::NativeFunc(|_env, args| {
let hash = require_typed_arg::<&HashMapRc>("hash_set", &args, 0)?;
let key = require_arg("hash_set", &args, 1)?;
let value = require_arg("hash_set", &args, 2)?;
hash.borrow_mut().insert(key.clone(), value.clone());
Ok(Value::HashMap(hash.clone()))
}),
);
env.define(
Symbol::from("+"),
Value::NativeFunc(|_env, args| {
let first_arg = require_arg("+", &args, 1)?;
let mut total = match first_arg {
Value::Int(_) => Ok(Value::Int(0.into())),
Value::Float(_) => Ok(Value::Float(0.0)),
Value::String(_) => Ok(Value::String("".into())),
_ => Err(RuntimeError {
msg: format!(
"Function \"+\" requires arguments to be numbers or strings; found {}",
first_arg
),
}),
}?;
for arg in args {
total = (&total + &arg).map_err(|_| RuntimeError {
msg: format!(
"Function \"+\" requires arguments to be numbers or strings; found {}",
arg
),
})?;
}
Ok(total)
}),
);
env.define(
Symbol::from("-"),
Value::NativeFunc(|_env, args| {
let a = require_arg("-", &args, 0)?;
let b = require_arg("-", &args, 1)?;
(a - b).map_err(|_| RuntimeError {
msg: String::from("Function \"-\" requires arguments to be numbers"),
})
}),
);
env.define(
Symbol::from("*"),
Value::NativeFunc(|_env, args| {
let mut product = Value::Int(1.into());
for arg in args {
product = (&product * &arg).map_err(|_| RuntimeError {
msg: format!(
"Function \"*\" requires arguments to be numbers; found {}",
arg
),
})?;
}
Ok(product)
}),
);
env.define(
Symbol::from("/"),
Value::NativeFunc(|_env, args| {
let a = require_arg("/", &args, 0)?;
let b = require_arg("/", &args, 1)?;
(a / b).map_err(|_| RuntimeError {
msg: String::from("Function \"/\" requires arguments to be numbers"),
})
}),
);
env.define(
Symbol::from("truncate"),
Value::NativeFunc(|_env, args| {
let a = require_arg("truncate", &args, 0)?;
let b = require_arg("truncate", &args, 1)?;
if let (Ok(a), Ok(b)) = (
TryInto::<IntType>::try_into(a),
TryInto::<IntType>::try_into(b),
) {
return Ok(Value::Int(a / b));
}
Err(RuntimeError {
msg: String::from("Function \"truncate\" requires arguments to be integers"),
})
}),
);
env.define(
Symbol::from("not"),
Value::NativeFunc(|_env, args| {
let a = require_arg("not", &args, 0)?;
let a: bool = a.into();
Ok(Value::from(!a))
}),
);
env.define(
Symbol::from("=="),
Value::NativeFunc(|_env, args| {
let a = require_arg("==", &args, 0)?;
let b = require_arg("==", &args, 1)?;
Ok(Value::from(a == b))
}),
);
env.define(
Symbol::from("!="),
Value::NativeFunc(|_env, args| {
let a = require_arg("!=", &args, 0)?;
let b = require_arg("!=", &args, 1)?;
Ok(Value::from(a != b))
}),
);
env.define(
Symbol::from("<"),
Value::NativeFunc(|_env, args| {
let a = require_arg("<", &args, 0)?;
let b = require_arg("<", &args, 1)?;
Ok(Value::from(a < b))
}),
);
env.define(
Symbol::from("<="),
Value::NativeFunc(|_env, args| {
let a = require_arg("<=", &args, 0)?;
let b = require_arg("<=", &args, 1)?;
Ok(Value::from(a <= b))
}),
);
env.define(
Symbol::from(">"),
Value::NativeFunc(|_env, args| {
let a = require_arg(">", &args, 0)?;
let b = require_arg(">", &args, 1)?;
Ok(Value::from(a > b))
}),
);
env.define(
Symbol::from(">="),
Value::NativeFunc(|_env, args| {
let a = require_arg(">=", &args, 0)?;
let b = require_arg(">=", &args, 1)?;
Ok(Value::from(a >= b))
}),
);
env.define(
Symbol::from("eval"),
Value::NativeFunc(|env, args| {
let expr = require_arg("eval", &args, 0)?;
eval(env, expr)
}),
);
env.define(
Symbol::from("apply"),
Value::NativeFunc(|env, args| {
let func = require_arg("apply", &args, 0)?;
let params = require_typed_arg::<&List>("apply", &args, 1)?;
eval(env, &Value::List(params.cons(func.clone())))
}),
);
env
}sourcepub fn cdr(&self) -> List
pub fn cdr(&self) -> List
Examples found in repository?
src/interpreter.rs (line 91)
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fn eval_inner(
env: Rc<RefCell<Env>>,
expression: &Value,
context: Context,
) -> Result<Value, RuntimeError> {
if context.quoting {
match expression {
Value::List(list) if *list != List::NIL => match &list.car()? {
Value::Symbol(Symbol(keyword)) if keyword == "comma" => {
// do nothing, handle it down below
}
_ => {
return list
.into_iter()
.map(|el| eval_inner(env.clone(), &el, context))
.collect::<Result<List, RuntimeError>>()
.map(Value::List);
}
},
_ => return Ok(expression.clone()),
}
}
match expression {
// look up symbol
Value::Symbol(symbol) => env.borrow().get(symbol).ok_or_else(|| RuntimeError {
msg: format!("\"{}\" is not defined", symbol),
}),
// s-expression
Value::List(list) if *list != List::NIL => {
match &list.car()? {
// special forms
Value::Symbol(Symbol(keyword)) if keyword == "comma" => {
eval_inner(env, &list.cdr().car()?, context.quoting(false))
}
Value::Symbol(Symbol(keyword)) if keyword == "quote" => {
eval_inner(env, &list.cdr().car()?, context.quoting(true))
}
Value::Symbol(Symbol(keyword)) if keyword == "define" || keyword == "set" => {
let args = &list.cdr().into_iter().collect::<Vec<Value>>();
let symbol = require_typed_arg::<&Symbol>(keyword, args, 0)?;
let value_expr = require_arg(keyword, args, 1)?;
let value = eval_inner(env.clone(), value_expr, context.found_tail(true))?;
if keyword == "define" {
env.borrow_mut().define(symbol.clone(), value.clone());
} else {
env.borrow_mut().set(symbol.clone(), value.clone())?;
}
Ok(value)
}
Value::Symbol(Symbol(keyword)) if keyword == "defmacro" => {
let args = &list.cdr().into_iter().collect::<Vec<Value>>();
let symbol = require_typed_arg::<&Symbol>(keyword, args, 0)?;
let argnames_list = require_typed_arg::<&List>(keyword, args, 1)?;
let argnames = value_to_argnames(argnames_list.clone())?;
let body = Rc::new(Value::List(list.cdr().cdr().cdr()));
let lambda = Value::Macro(Lambda {
closure: env.clone(),
argnames,
body,
});
env.borrow_mut().define(symbol.clone(), lambda);
Ok(Value::NIL)
}
Value::Symbol(Symbol(keyword)) if keyword == "defun" => {
let args = &list.cdr().into_iter().collect::<Vec<Value>>();
let symbol = require_typed_arg::<&Symbol>(keyword, args, 0)?;
let argnames_list = require_typed_arg::<&List>(keyword, args, 1)?;
let argnames = value_to_argnames(argnames_list.clone())?;
let body = Rc::new(Value::List(list.cdr().cdr().cdr()));
let lambda = Value::Lambda(Lambda {
closure: env.clone(),
argnames,
body,
});
env.borrow_mut().define(symbol.clone(), lambda);
Ok(Value::NIL)
}
Value::Symbol(Symbol(keyword)) if keyword == "lambda" => {
let args = &list.cdr().into_iter().collect::<Vec<Value>>();
let argnames_list = require_typed_arg::<&List>(keyword, args, 0)?;
let argnames = value_to_argnames(argnames_list.clone())?;
let body = Rc::new(Value::List(list.cdr().cdr()));
Ok(Value::Lambda(Lambda {
closure: env,
argnames,
body,
}))
}
Value::Symbol(Symbol(keyword)) if keyword == "let" => {
let let_env = Rc::new(RefCell::new(Env::extend(env)));
let args = &list.cdr().into_iter().collect::<Vec<Value>>();
let declarations = require_typed_arg::<&List>(keyword, args, 0)?;
for decl in declarations.into_iter() {
let decl = &decl;
let decl_cons: &List = decl.try_into().map_err(|_| RuntimeError {
msg: format!("Expected declaration clause, found {}", decl),
})?;
let symbol = &decl_cons.car()?;
let symbol: &Symbol = symbol.try_into().map_err(|_| RuntimeError {
msg: format!("Expected symbol for let declaration, found {}", symbol),
})?;
let expr = &decl_cons.cdr().car()?;
let result = eval_inner(let_env.clone(), expr, context.found_tail(true))?;
let_env.borrow_mut().define(symbol.clone(), result);
}
let body = &Value::List(list.cdr().cdr());
let body: &List = body.try_into().map_err(|_| RuntimeError {
msg: format!(
"Expected expression(s) after let-declarations, found {}",
body
),
})?;
eval_block_inner(let_env, body.into_iter(), context)
}
Value::Symbol(Symbol(keyword)) if keyword == "begin" => {
eval_block_inner(env, list.cdr().into_iter(), context)
}
Value::Symbol(Symbol(keyword)) if keyword == "cond" => {
let clauses = list.cdr();
for clause in clauses.into_iter() {
let clause = &clause;
let clause: &List = clause.try_into().map_err(|_| RuntimeError {
msg: format!("Expected conditional clause, found {}", clause),
})?;
let condition = &clause.car()?;
let then = &clause.cdr().car()?;
if eval_inner(env.clone(), condition, context.found_tail(true))?.into() {
return eval_inner(env, then, context);
}
}
Ok(Value::NIL)
}
Value::Symbol(Symbol(keyword)) if keyword == "if" => {
let args = &list.cdr().into_iter().collect::<Vec<Value>>();
let condition = require_arg(keyword, args, 0)?;
let then_expr = require_arg(keyword, args, 1)?;
let else_expr = require_arg(keyword, args, 2).ok();
if eval_inner(env.clone(), condition, context.found_tail(true))?.into() {
eval_inner(env, then_expr, context)
} else {
else_expr
.map(|expr| eval_inner(env, &expr, context))
.unwrap_or(Ok(Value::NIL))
}
}
Value::Symbol(Symbol(keyword)) if keyword == "and" || keyword == "or" => {
let args = &list.cdr().into_iter().collect::<Vec<Value>>();
let is_or = keyword.as_str() == "or";
let mut last_result: Option<Value> = None;
for arg in args {
let result = eval_inner(env.clone(), arg, context.found_tail(true))?;
let truthy: bool = (&result).into();
if is_or == truthy {
return Ok(result);
}
last_result = Some(result);
}
Ok(if let Some(last_result) = last_result {
last_result
} else {
// there were zero arguments
(!is_or).into()
})
}
// function call or macro expand
_ => {
let mut func_or_macro =
eval_inner(env.clone(), &list.car()?, context.found_tail(true))?;
if matches!(func_or_macro, Value::Macro(_)) {
let args = list.into_iter().skip(1).collect::<Vec<Value>>();
let expanded =
call_function_or_macro(env.clone(), &mut func_or_macro, args)?;
eval_inner(env.clone(), &expanded, Context::new())
} else {
let args = list
.into_iter()
.skip(1)
.map(|car| eval_inner(env.clone(), &car, context.found_tail(true)))
.collect::<Result<Vec<Value>, RuntimeError>>()?;
if !context.found_tail && context.in_func {
Ok(Value::TailCall {
func: Rc::new(func_or_macro),
args,
})
} else {
let mut res =
call_function_or_macro(env.clone(), &mut func_or_macro, args);
while let Ok(Value::TailCall { func, args }) = res {
res = call_function_or_macro(env.clone(), func.as_ref(), args);
}
res
}
}
}
}
}
// plain value
_ => Ok(expression.clone()),
}
}More examples
src/default_environment.rs (line 117)
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pub fn default_env() -> Env {
let mut env = Env::new();
env.define(
Symbol::from("print"),
Value::NativeFunc(|_env, args| {
let expr = require_arg("print", &args, 0)?;
println!("{}", &expr);
Ok(expr.clone())
}),
);
env.define(
Symbol::from("is_null"),
Value::NativeFunc(|_env, args| {
let val = require_arg("is_null", &args, 0)?;
Ok(Value::from(*val == Value::NIL))
}),
);
env.define(
Symbol::from("is_number"),
Value::NativeFunc(|_env, args| {
let val = require_arg("is_number", &args, 0)?;
Ok(match val {
Value::Int(_) => Value::True,
Value::Float(_) => Value::True,
_ => Value::NIL,
})
}),
);
env.define(
Symbol::from("is_symbol"),
Value::NativeFunc(|_env, args| {
let val = require_arg("is_symbol", &args, 0)?;
Ok(match val {
Value::Symbol(_) => Value::True,
_ => Value::NIL,
})
}),
);
env.define(
Symbol::from("is_boolean"),
Value::NativeFunc(|_env, args| {
let val = require_arg("is_boolean", &args, 0)?;
Ok(match val {
Value::True => Value::True,
Value::False => Value::True,
_ => Value::NIL,
})
}),
);
env.define(
Symbol::from("is_procedure"),
Value::NativeFunc(|_env, args| {
let val = require_arg("is_procedure", &args, 0)?;
Ok(match val {
Value::Lambda(_) => Value::True,
Value::NativeFunc(_) => Value::True,
_ => Value::NIL,
})
}),
);
env.define(
Symbol::from("is_pair"),
Value::NativeFunc(|_env, args| {
let val = require_arg("is_pair", &args, 0)?;
Ok(match val {
Value::List(_) => Value::True,
_ => Value::NIL,
})
}),
);
env.define(
Symbol::from("car"),
Value::NativeFunc(|_env, args| {
let list = require_typed_arg::<&List>("car", &args, 0)?;
list.car()
}),
);
env.define(
Symbol::from("cdr"),
Value::NativeFunc(|_env, args| {
let list = require_typed_arg::<&List>("cdr", &args, 0)?;
Ok(Value::List(list.cdr()))
}),
);
env.define(
Symbol::from("cons"),
Value::NativeFunc(|_env, args| {
let car = require_arg("cons", &args, 0)?;
let cdr = require_typed_arg::<&List>("cons", &args, 1)?;
Ok(Value::List(cdr.cons(car.clone())))
}),
);
env.define(
Symbol::from("list"),
Value::NativeFunc(|_env, args| Ok(Value::List(args.iter().collect::<List>()))),
);
env.define(
Symbol::from("nth"),
Value::NativeFunc(|_env, args| {
let index = require_typed_arg::<IntType>("nth", &args, 0)?;
let list = require_typed_arg::<&List>("nth", &args, 1)?;
let index = TryInto::<usize>::try_into(index).map_err(|_| RuntimeError {
msg: "Failed converting to `usize`".to_owned(),
})?;
Ok(list.into_iter().nth(index).unwrap_or(Value::NIL))
}),
);
env.define(
Symbol::from("sort"),
Value::NativeFunc(|_env, args| {
let list = require_typed_arg::<&List>("sort", &args, 0)?;
let mut v: Vec<Value> = list.into_iter().collect();
v.sort();
Ok(Value::List(v.into_iter().collect()))
}),
);
env.define(
Symbol::from("reverse"),
Value::NativeFunc(|_env, args| {
let list = require_typed_arg::<&List>("reverse", &args, 0)?;
let mut v: Vec<Value> = list.into_iter().collect();
v.reverse();
Ok(Value::List(v.into_iter().collect()))
}),
);
env.define(
Symbol::from("map"),
Value::NativeFunc(|env, args| {
let func = require_arg("map", &args, 0)?;
let list = require_typed_arg::<&List>("map", &args, 1)?;
list.into_iter()
.map(|val| {
let expr = lisp! { ({func.clone()} (quote {val})) };
eval(env.clone(), &expr)
})
.collect::<Result<List, RuntimeError>>()
.map(Value::List)
}),
);
// 🦀 Oh the poor `filter`, you must feel really sad being unused.
env.define(
Symbol::from("filter"),
Value::NativeFunc(|env, args| {
let func = require_arg("filter", &args, 0)?;
let list = require_typed_arg::<&List>("filter", &args, 1)?;
list.into_iter()
.filter_map(|val: Value| -> Option<Result<Value, RuntimeError>> {
let expr = lisp! { ({func.clone()} (quote {val.clone()})) };
match eval(env.clone(), &expr) {
Ok(matches) => {
if matches.into() {
Some(Ok(val))
} else {
None
}
}
Err(e) => Some(Err(e)),
}
})
.collect::<Result<List, RuntimeError>>()
.map(Value::List)
}),
);
env.define(
Symbol::from("length"),
Value::NativeFunc(|_env, args| {
let list = require_typed_arg::<&List>("length", &args, 0)?;
cfg_if! {
if #[cfg(feature = "bigint")] {
Ok(Value::Int(list.into_iter().len().into()))
} else {
Ok(Value::Int(list.into_iter().len() as IntType))
}
}
}),
);
env.define(
Symbol::from("range"),
Value::NativeFunc(|_env, args| {
let start = require_typed_arg::<IntType>("range", &args, 0)?;
let end = require_typed_arg::<IntType>("range", &args, 1)?;
let mut current = start;
Ok(Value::List(
std::iter::from_fn(move || {
if current == end {
None
} else {
let res = Some(current.clone());
current += 1;
res
}
})
.map(Value::from)
.collect(),
))
}),
);
env.define(
Symbol::from("hash"),
Value::NativeFunc(|_env, args| {
let chunks = args.chunks(2);
let mut hash = HashMap::new();
for pair in chunks {
let key = pair.get(0).unwrap();
let value = pair.get(1);
if let Some(value) = value {
hash.insert(key.clone(), value.clone());
} else {
return Err(RuntimeError {
msg: format!("Must pass an even number of arguments to 'hash', because they're used as key/value pairs; found extra argument {}", key)
});
}
}
Ok(Value::HashMap(Rc::new(RefCell::new(hash))))
}),
);
env.define(
Symbol::from("hash_get"),
Value::NativeFunc(|_env, args| {
let hash = require_typed_arg::<&HashMapRc>("hash_get", &args, 0)?;
let key = require_arg("hash_get", &args, 1)?;
Ok(hash
.borrow()
.get(key)
.map(|v| v.clone())
.unwrap_or(Value::NIL))
}),
);
env.define(
Symbol::from("hash_set"),
Value::NativeFunc(|_env, args| {
let hash = require_typed_arg::<&HashMapRc>("hash_set", &args, 0)?;
let key = require_arg("hash_set", &args, 1)?;
let value = require_arg("hash_set", &args, 2)?;
hash.borrow_mut().insert(key.clone(), value.clone());
Ok(Value::HashMap(hash.clone()))
}),
);
env.define(
Symbol::from("+"),
Value::NativeFunc(|_env, args| {
let first_arg = require_arg("+", &args, 1)?;
let mut total = match first_arg {
Value::Int(_) => Ok(Value::Int(0.into())),
Value::Float(_) => Ok(Value::Float(0.0)),
Value::String(_) => Ok(Value::String("".into())),
_ => Err(RuntimeError {
msg: format!(
"Function \"+\" requires arguments to be numbers or strings; found {}",
first_arg
),
}),
}?;
for arg in args {
total = (&total + &arg).map_err(|_| RuntimeError {
msg: format!(
"Function \"+\" requires arguments to be numbers or strings; found {}",
arg
),
})?;
}
Ok(total)
}),
);
env.define(
Symbol::from("-"),
Value::NativeFunc(|_env, args| {
let a = require_arg("-", &args, 0)?;
let b = require_arg("-", &args, 1)?;
(a - b).map_err(|_| RuntimeError {
msg: String::from("Function \"-\" requires arguments to be numbers"),
})
}),
);
env.define(
Symbol::from("*"),
Value::NativeFunc(|_env, args| {
let mut product = Value::Int(1.into());
for arg in args {
product = (&product * &arg).map_err(|_| RuntimeError {
msg: format!(
"Function \"*\" requires arguments to be numbers; found {}",
arg
),
})?;
}
Ok(product)
}),
);
env.define(
Symbol::from("/"),
Value::NativeFunc(|_env, args| {
let a = require_arg("/", &args, 0)?;
let b = require_arg("/", &args, 1)?;
(a / b).map_err(|_| RuntimeError {
msg: String::from("Function \"/\" requires arguments to be numbers"),
})
}),
);
env.define(
Symbol::from("truncate"),
Value::NativeFunc(|_env, args| {
let a = require_arg("truncate", &args, 0)?;
let b = require_arg("truncate", &args, 1)?;
if let (Ok(a), Ok(b)) = (
TryInto::<IntType>::try_into(a),
TryInto::<IntType>::try_into(b),
) {
return Ok(Value::Int(a / b));
}
Err(RuntimeError {
msg: String::from("Function \"truncate\" requires arguments to be integers"),
})
}),
);
env.define(
Symbol::from("not"),
Value::NativeFunc(|_env, args| {
let a = require_arg("not", &args, 0)?;
let a: bool = a.into();
Ok(Value::from(!a))
}),
);
env.define(
Symbol::from("=="),
Value::NativeFunc(|_env, args| {
let a = require_arg("==", &args, 0)?;
let b = require_arg("==", &args, 1)?;
Ok(Value::from(a == b))
}),
);
env.define(
Symbol::from("!="),
Value::NativeFunc(|_env, args| {
let a = require_arg("!=", &args, 0)?;
let b = require_arg("!=", &args, 1)?;
Ok(Value::from(a != b))
}),
);
env.define(
Symbol::from("<"),
Value::NativeFunc(|_env, args| {
let a = require_arg("<", &args, 0)?;
let b = require_arg("<", &args, 1)?;
Ok(Value::from(a < b))
}),
);
env.define(
Symbol::from("<="),
Value::NativeFunc(|_env, args| {
let a = require_arg("<=", &args, 0)?;
let b = require_arg("<=", &args, 1)?;
Ok(Value::from(a <= b))
}),
);
env.define(
Symbol::from(">"),
Value::NativeFunc(|_env, args| {
let a = require_arg(">", &args, 0)?;
let b = require_arg(">", &args, 1)?;
Ok(Value::from(a > b))
}),
);
env.define(
Symbol::from(">="),
Value::NativeFunc(|_env, args| {
let a = require_arg(">=", &args, 0)?;
let b = require_arg(">=", &args, 1)?;
Ok(Value::from(a >= b))
}),
);
env.define(
Symbol::from("eval"),
Value::NativeFunc(|env, args| {
let expr = require_arg("eval", &args, 0)?;
eval(env, expr)
}),
);
env.define(
Symbol::from("apply"),
Value::NativeFunc(|env, args| {
let func = require_arg("apply", &args, 0)?;
let params = require_typed_arg::<&List>("apply", &args, 1)?;
eval(env, &Value::List(params.cons(func.clone())))
}),
);
env
}sourcepub fn cons(&self, val: Value) -> List
pub fn cons(&self, val: Value) -> List
Examples found in repository?
src/default_environment.rs (line 127)
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pub fn default_env() -> Env {
let mut env = Env::new();
env.define(
Symbol::from("print"),
Value::NativeFunc(|_env, args| {
let expr = require_arg("print", &args, 0)?;
println!("{}", &expr);
Ok(expr.clone())
}),
);
env.define(
Symbol::from("is_null"),
Value::NativeFunc(|_env, args| {
let val = require_arg("is_null", &args, 0)?;
Ok(Value::from(*val == Value::NIL))
}),
);
env.define(
Symbol::from("is_number"),
Value::NativeFunc(|_env, args| {
let val = require_arg("is_number", &args, 0)?;
Ok(match val {
Value::Int(_) => Value::True,
Value::Float(_) => Value::True,
_ => Value::NIL,
})
}),
);
env.define(
Symbol::from("is_symbol"),
Value::NativeFunc(|_env, args| {
let val = require_arg("is_symbol", &args, 0)?;
Ok(match val {
Value::Symbol(_) => Value::True,
_ => Value::NIL,
})
}),
);
env.define(
Symbol::from("is_boolean"),
Value::NativeFunc(|_env, args| {
let val = require_arg("is_boolean", &args, 0)?;
Ok(match val {
Value::True => Value::True,
Value::False => Value::True,
_ => Value::NIL,
})
}),
);
env.define(
Symbol::from("is_procedure"),
Value::NativeFunc(|_env, args| {
let val = require_arg("is_procedure", &args, 0)?;
Ok(match val {
Value::Lambda(_) => Value::True,
Value::NativeFunc(_) => Value::True,
_ => Value::NIL,
})
}),
);
env.define(
Symbol::from("is_pair"),
Value::NativeFunc(|_env, args| {
let val = require_arg("is_pair", &args, 0)?;
Ok(match val {
Value::List(_) => Value::True,
_ => Value::NIL,
})
}),
);
env.define(
Symbol::from("car"),
Value::NativeFunc(|_env, args| {
let list = require_typed_arg::<&List>("car", &args, 0)?;
list.car()
}),
);
env.define(
Symbol::from("cdr"),
Value::NativeFunc(|_env, args| {
let list = require_typed_arg::<&List>("cdr", &args, 0)?;
Ok(Value::List(list.cdr()))
}),
);
env.define(
Symbol::from("cons"),
Value::NativeFunc(|_env, args| {
let car = require_arg("cons", &args, 0)?;
let cdr = require_typed_arg::<&List>("cons", &args, 1)?;
Ok(Value::List(cdr.cons(car.clone())))
}),
);
env.define(
Symbol::from("list"),
Value::NativeFunc(|_env, args| Ok(Value::List(args.iter().collect::<List>()))),
);
env.define(
Symbol::from("nth"),
Value::NativeFunc(|_env, args| {
let index = require_typed_arg::<IntType>("nth", &args, 0)?;
let list = require_typed_arg::<&List>("nth", &args, 1)?;
let index = TryInto::<usize>::try_into(index).map_err(|_| RuntimeError {
msg: "Failed converting to `usize`".to_owned(),
})?;
Ok(list.into_iter().nth(index).unwrap_or(Value::NIL))
}),
);
env.define(
Symbol::from("sort"),
Value::NativeFunc(|_env, args| {
let list = require_typed_arg::<&List>("sort", &args, 0)?;
let mut v: Vec<Value> = list.into_iter().collect();
v.sort();
Ok(Value::List(v.into_iter().collect()))
}),
);
env.define(
Symbol::from("reverse"),
Value::NativeFunc(|_env, args| {
let list = require_typed_arg::<&List>("reverse", &args, 0)?;
let mut v: Vec<Value> = list.into_iter().collect();
v.reverse();
Ok(Value::List(v.into_iter().collect()))
}),
);
env.define(
Symbol::from("map"),
Value::NativeFunc(|env, args| {
let func = require_arg("map", &args, 0)?;
let list = require_typed_arg::<&List>("map", &args, 1)?;
list.into_iter()
.map(|val| {
let expr = lisp! { ({func.clone()} (quote {val})) };
eval(env.clone(), &expr)
})
.collect::<Result<List, RuntimeError>>()
.map(Value::List)
}),
);
// 🦀 Oh the poor `filter`, you must feel really sad being unused.
env.define(
Symbol::from("filter"),
Value::NativeFunc(|env, args| {
let func = require_arg("filter", &args, 0)?;
let list = require_typed_arg::<&List>("filter", &args, 1)?;
list.into_iter()
.filter_map(|val: Value| -> Option<Result<Value, RuntimeError>> {
let expr = lisp! { ({func.clone()} (quote {val.clone()})) };
match eval(env.clone(), &expr) {
Ok(matches) => {
if matches.into() {
Some(Ok(val))
} else {
None
}
}
Err(e) => Some(Err(e)),
}
})
.collect::<Result<List, RuntimeError>>()
.map(Value::List)
}),
);
env.define(
Symbol::from("length"),
Value::NativeFunc(|_env, args| {
let list = require_typed_arg::<&List>("length", &args, 0)?;
cfg_if! {
if #[cfg(feature = "bigint")] {
Ok(Value::Int(list.into_iter().len().into()))
} else {
Ok(Value::Int(list.into_iter().len() as IntType))
}
}
}),
);
env.define(
Symbol::from("range"),
Value::NativeFunc(|_env, args| {
let start = require_typed_arg::<IntType>("range", &args, 0)?;
let end = require_typed_arg::<IntType>("range", &args, 1)?;
let mut current = start;
Ok(Value::List(
std::iter::from_fn(move || {
if current == end {
None
} else {
let res = Some(current.clone());
current += 1;
res
}
})
.map(Value::from)
.collect(),
))
}),
);
env.define(
Symbol::from("hash"),
Value::NativeFunc(|_env, args| {
let chunks = args.chunks(2);
let mut hash = HashMap::new();
for pair in chunks {
let key = pair.get(0).unwrap();
let value = pair.get(1);
if let Some(value) = value {
hash.insert(key.clone(), value.clone());
} else {
return Err(RuntimeError {
msg: format!("Must pass an even number of arguments to 'hash', because they're used as key/value pairs; found extra argument {}", key)
});
}
}
Ok(Value::HashMap(Rc::new(RefCell::new(hash))))
}),
);
env.define(
Symbol::from("hash_get"),
Value::NativeFunc(|_env, args| {
let hash = require_typed_arg::<&HashMapRc>("hash_get", &args, 0)?;
let key = require_arg("hash_get", &args, 1)?;
Ok(hash
.borrow()
.get(key)
.map(|v| v.clone())
.unwrap_or(Value::NIL))
}),
);
env.define(
Symbol::from("hash_set"),
Value::NativeFunc(|_env, args| {
let hash = require_typed_arg::<&HashMapRc>("hash_set", &args, 0)?;
let key = require_arg("hash_set", &args, 1)?;
let value = require_arg("hash_set", &args, 2)?;
hash.borrow_mut().insert(key.clone(), value.clone());
Ok(Value::HashMap(hash.clone()))
}),
);
env.define(
Symbol::from("+"),
Value::NativeFunc(|_env, args| {
let first_arg = require_arg("+", &args, 1)?;
let mut total = match first_arg {
Value::Int(_) => Ok(Value::Int(0.into())),
Value::Float(_) => Ok(Value::Float(0.0)),
Value::String(_) => Ok(Value::String("".into())),
_ => Err(RuntimeError {
msg: format!(
"Function \"+\" requires arguments to be numbers or strings; found {}",
first_arg
),
}),
}?;
for arg in args {
total = (&total + &arg).map_err(|_| RuntimeError {
msg: format!(
"Function \"+\" requires arguments to be numbers or strings; found {}",
arg
),
})?;
}
Ok(total)
}),
);
env.define(
Symbol::from("-"),
Value::NativeFunc(|_env, args| {
let a = require_arg("-", &args, 0)?;
let b = require_arg("-", &args, 1)?;
(a - b).map_err(|_| RuntimeError {
msg: String::from("Function \"-\" requires arguments to be numbers"),
})
}),
);
env.define(
Symbol::from("*"),
Value::NativeFunc(|_env, args| {
let mut product = Value::Int(1.into());
for arg in args {
product = (&product * &arg).map_err(|_| RuntimeError {
msg: format!(
"Function \"*\" requires arguments to be numbers; found {}",
arg
),
})?;
}
Ok(product)
}),
);
env.define(
Symbol::from("/"),
Value::NativeFunc(|_env, args| {
let a = require_arg("/", &args, 0)?;
let b = require_arg("/", &args, 1)?;
(a / b).map_err(|_| RuntimeError {
msg: String::from("Function \"/\" requires arguments to be numbers"),
})
}),
);
env.define(
Symbol::from("truncate"),
Value::NativeFunc(|_env, args| {
let a = require_arg("truncate", &args, 0)?;
let b = require_arg("truncate", &args, 1)?;
if let (Ok(a), Ok(b)) = (
TryInto::<IntType>::try_into(a),
TryInto::<IntType>::try_into(b),
) {
return Ok(Value::Int(a / b));
}
Err(RuntimeError {
msg: String::from("Function \"truncate\" requires arguments to be integers"),
})
}),
);
env.define(
Symbol::from("not"),
Value::NativeFunc(|_env, args| {
let a = require_arg("not", &args, 0)?;
let a: bool = a.into();
Ok(Value::from(!a))
}),
);
env.define(
Symbol::from("=="),
Value::NativeFunc(|_env, args| {
let a = require_arg("==", &args, 0)?;
let b = require_arg("==", &args, 1)?;
Ok(Value::from(a == b))
}),
);
env.define(
Symbol::from("!="),
Value::NativeFunc(|_env, args| {
let a = require_arg("!=", &args, 0)?;
let b = require_arg("!=", &args, 1)?;
Ok(Value::from(a != b))
}),
);
env.define(
Symbol::from("<"),
Value::NativeFunc(|_env, args| {
let a = require_arg("<", &args, 0)?;
let b = require_arg("<", &args, 1)?;
Ok(Value::from(a < b))
}),
);
env.define(
Symbol::from("<="),
Value::NativeFunc(|_env, args| {
let a = require_arg("<=", &args, 0)?;
let b = require_arg("<=", &args, 1)?;
Ok(Value::from(a <= b))
}),
);
env.define(
Symbol::from(">"),
Value::NativeFunc(|_env, args| {
let a = require_arg(">", &args, 0)?;
let b = require_arg(">", &args, 1)?;
Ok(Value::from(a > b))
}),
);
env.define(
Symbol::from(">="),
Value::NativeFunc(|_env, args| {
let a = require_arg(">=", &args, 0)?;
let b = require_arg(">=", &args, 1)?;
Ok(Value::from(a >= b))
}),
);
env.define(
Symbol::from("eval"),
Value::NativeFunc(|env, args| {
let expr = require_arg("eval", &args, 0)?;
eval(env, expr)
}),
);
env.define(
Symbol::from("apply"),
Value::NativeFunc(|env, args| {
let func = require_arg("apply", &args, 0)?;
let params = require_typed_arg::<&List>("apply", &args, 1)?;
eval(env, &Value::List(params.cons(func.clone())))
}),
);
env
}