maurice/snix
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

feat(tvix/repl): Allow binding variables at the top-level

Browse source 
Allow binding variables at the REPL's toplevel in the same way the Nix
REPL does, using the syntax <ident> = <expr>. This fully, strictly
evaluates the value and sets it in the repl's "env", which gets passed
in at the toplevel when evaluating expressions.

The laziness behavior differs from Nix's, but I think this is good:

    ❯ nix repl
    Welcome to Nix version 2.3.18. Type :? for help.

    nix-repl> x = builtins.trace "x" 1

    nix-repl> x
    trace: x
    1

    nix-repl> x
    1

vs tvix:

    tvix-repl> x = builtins.trace "x" 1
    trace: "x" :: string
    tvix-repl> x
    => 1 :: int
    tvix-repl> x
    => 1 :: int

Bug: https://b.tvl.fyi/issues/371
Change-Id: Ieb2d626b7195fa87be638c9a4dae2eee45eb9ab1
Reviewed-on: https://cl.tvl.fyi/c/depot/+/11954
Reviewed-by: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
Autosubmit: aspen <root@gws.fyi>
This commit is contained in:
Aspen Smith 2024-07-04 23:46:20 -04:00 • committed by clbot
parent ac3d717944
commit fc63594631
6 changed files with 157 additions and 16 deletions
Download patch file Download diff file Expand all files Collapse all files

46
tvix/cli/src/repl.rs
View file

@ -1,10 +1,13 @@
use std::path::PathBuf;
use std::rc::Rc;
use std::{collections::HashMap, path::PathBuf};
use rustyline::{error::ReadlineError, Editor};
use smol_str::SmolStr;
use tvix_eval::Value;
use tvix_glue::tvix_store_io::TvixStoreIO;
use crate::{interpret, AllowIncomplete, Args, IncompleteInput};
use crate::evaluate;
use crate::{assignment::Assignment, interpret, AllowIncomplete, Args, IncompleteInput};
fn state_dir() -> Option<PathBuf> {
let mut path = dirs::data_dir();
@ -17,6 +20,7 @@ fn state_dir() -> Option<PathBuf> {
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum ReplCommand<'a> {
Expr(&'a str),
Assign(Assignment<'a>),
Explain(&'a str),
Print(&'a str),
Quit,
@ -29,11 +33,12 @@ Welcome to the Tvix REPL!
The following commands are supported:
<expr> Evaluate a Nix language expression and print the result, along with its inferred type
:d <expr> Evaluate a Nix language expression and print a detailed description of the result
:p <expr> Evaluate a Nix language expression and print the result recursively
:q Exit the REPL
:?, :h Display this help text
<expr> Evaluate a Nix language expression and print the result, along with its inferred type
<x> = <expr> Bind the result of an expression to a variable
:d <expr> Evaluate a Nix language expression and print a detailed description of the result
:p <expr> Evaluate a Nix language expression and print the result recursively
:q Exit the REPL
:?, :h Display this help text
";
pub fn parse(input: &'a str) -> Self {
@ -52,6 +57,10 @@ The following commands are supported:
}
}
if let Some(assignment) = Assignment::parse(input) {
return Self::Assign(assignment);
}
Self::Expr(input)
}
}
@ -61,6 +70,8 @@ pub struct Repl {
/// In-progress multiline input, when the input so far doesn't parse as a complete expression
multiline_input: Option<String>,
rl: Editor<()>,
/// Local variables defined at the top-level in the repl
env: HashMap<SmolStr, Value>,
}
impl Repl {
@ -69,6 +80,7 @@ impl Repl {
Self {
multiline_input: None,
rl,
env: HashMap::new(),
}
}
@ -125,7 +137,25 @@ impl Repl {
args,
false,
AllowIncomplete::Allow,
Some(&self.env),
),
ReplCommand::Assign(Assignment { ident, value }) => {
match evaluate(
Rc::clone(&io_handle),
&value.to_string(), /* FIXME: don't re-parse */
None,
args,
AllowIncomplete::Allow,
Some(&self.env),
) {
Ok(Some(value)) => {
self.env.insert(ident.into(), value);
Ok(true)
}
Ok(None) => Ok(true),
Err(incomplete) => Err(incomplete),
}
}
ReplCommand::Explain(input) => interpret(
Rc::clone(&io_handle),
input,
@ -133,6 +163,7 @@ impl Repl {
args,
true,
AllowIncomplete::Allow,
Some(&self.env),
),
ReplCommand::Print(input) => interpret(
Rc::clone(&io_handle),
@ -144,6 +175,7 @@ impl Repl {
},
false,
AllowIncomplete::Allow,
Some(&self.env),
),
};