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use myslip::parse::parsetree::parse_to_ast;
use myslip::sexp::{SExp::*, SLeaf::{Nil, Let}, util::scons};
use std::{io, io::Write};
fn main() {
match repl() {
Ok(()) => println!("bye :)"),
Err(e) => println!("Error: {}", e),
}
}
fn prompt_line(stdin: &io::Stdin, stdout: &mut io::Stdout) -> Result<(bool, String), io::Error> {
let mut line = String::new();
print!("> ");
match stdout.flush() {
Ok(_) => (),
Err(_) => println!("Enter s-expression:"),
};
let code = stdin.read_line(&mut line)?;
Ok((code == 0, line))
}
fn repl() -> Result<(), io::Error> {
let stdin = io::stdin();
let mut stdout = io::stdout();
let mut binds = vec![];
loop {
let (eof, input) = prompt_line(&stdin, &mut stdout)?;
if eof || input == "exit\n" {
break;
}
let mut expression = match parse_to_ast(&input) {
Ok(SCons(a, b)) if *b == Atom(Nil) => *a,
Ok(t) => t,
Err(e) => {
println!("Syntax error: {}", e);
continue;
},
};
match &expression {
SCons(l, r) if **l == Atom(Let) => match scons(expression.clone(), Nil).type_check() {
Ok(_) => {
binds.push(expression);
println!("Bind saved");
continue;
},
Err(e) => {
println!("Type error: {e}");
continue;
}
},
_ => (),
}
for i in 1..=binds.len() {
expression = scons(binds[binds.len() - i].clone(), expression);
}
let ty = match expression
.type_check()
.map_err(|e| e.to_string()) {
Ok(t) => t,
Err(e) => {
println!("Type error: {}", e);
continue;
},
};
let result = match expression.multistep() {
Ok(t) => t,
Err(e) => {
println!("Runtime error: {}", e);
continue;
},
};
println!("{} : {}", result, ty);
}
Ok(())
}
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