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

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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
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41
tvix/cli/src/main.rs
View file

@ -1,7 +1,10 @@
mod assignment;
mod repl;
use clap::Parser;
use repl::Repl;
use smol_str::SmolStr;
use std::collections::HashMap;
use std::rc::Rc;
use std::{fs, path::PathBuf};
use tracing::{instrument, Level, Span};
@ -150,18 +153,15 @@ impl AllowIncomplete {
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
struct IncompleteInput;
/// Interprets the given code snippet, printing out warnings, errors
/// and the result itself. The return value indicates whether
/// evaluation succeeded.
#[instrument(skip_all, fields(indicatif.pb_show=1))]
fn interpret(
/// Interprets the given code snippet, printing out warnings and errors and returning the result
fn evaluate(
tvix_store_io: Rc<TvixStoreIO>,
code: &str,
path: Option<PathBuf>,
args: &Args,
explain: bool,
allow_incomplete: AllowIncomplete,
) -> Result<bool, IncompleteInput> {
env: Option<&HashMap<SmolStr, Value>>,
) -> Result<Option<Value>, IncompleteInput> {
let span = Span::current();
span.pb_start();
span.pb_set_style(&tvix_tracing::PB_SPINNER_STYLE);
@ -173,6 +173,9 @@ fn interpret(
);
eval.strict = args.strict;
eval.builtins.extend(impure_builtins());
if let Some(env) = env {
eval.env = Some(env);
}
add_derivation_builtins(&mut eval, Rc::clone(&tvix_store_io));
add_fetcher_builtins(&mut eval, Rc::clone(&tvix_store_io));
add_import_builtins(&mut eval, tvix_store_io);
@ -226,7 +229,25 @@ fn interpret(
}
}
if let Some(value) = result.value.as_ref() {
Ok(result.value)
}
/// Interprets the given code snippet, printing out warnings, errors
/// and the result itself. The return value indicates whether
/// evaluation succeeded.
#[instrument(skip_all, fields(indicatif.pb_show=1))]
fn interpret(
tvix_store_io: Rc<TvixStoreIO>,
code: &str,
path: Option<PathBuf>,
args: &Args,
explain: bool,
allow_incomplete: AllowIncomplete,
env: Option<&HashMap<SmolStr, Value>>,
) -> Result<bool, IncompleteInput> {
let result = evaluate(tvix_store_io, code, path, args, allow_incomplete, env)?;
if let Some(value) = result.as_ref() {
if explain {
println!("=> {}", value.explain());
} else {
@ -235,7 +256,7 @@ fn interpret(
}
// inform the caller about any errors
Ok(result.errors.is_empty())
Ok(result.is_some())
}
/// Interpret the given code snippet, but only run the Tvix compiler
@ -298,6 +319,7 @@ fn main() {
&args,
false,
AllowIncomplete::RequireComplete,
None, // TODO(aspen): Pass in --arg/--argstr here
)
.unwrap()
{
@ -325,6 +347,7 @@ fn run_file(io_handle: Rc<TvixStoreIO>, mut path: PathBuf, args: &Args) {
args,
false,
AllowIncomplete::RequireComplete,
None,
)
.unwrap()
};