Merge "Add repl-overlays" into main

This commit is contained in:
rebecca “wiggles” turner 2024-04-09 05:29:48 +00:00 committed by Gerrit Code Review
commit a95c62673b
25 changed files with 355 additions and 3 deletions

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@ -0,0 +1,36 @@
---
synopsis: Add `repl-overlays` option
prs: 10203
cls: 504
---
A `repl-overlays` option has been added, which specifies files that can overlay
and modify the top-level bindings in `nix repl`. For example, with the
following contents in `~/.config/nix/repl.nix`:
```nix
info: final: prev: let
optionalAttrs = predicate: attrs:
if predicate
then attrs
else {};
in
optionalAttrs (prev ? legacyPackages && prev.legacyPackages ? ${info.currentSystem})
{
pkgs = prev.legacyPackages.${info.currentSystem};
}
```
We can run `nix repl` and use `pkgs` to refer to `legacyPackages.${currentSystem}`:
```ShellSession
$ nix repl --repl-overlays ~/.config/nix/repl.nix nixpkgs
Lix 2.90.0
Type :? for help.
Loading installable 'flake:nixpkgs#'...
Added 5 variables.
Loading 'repl-overlays'...
Added 6 variables.
nix-repl> pkgs.bash
«derivation /nix/store/g08b5vkwwh0j8ic9rkmd8mpj878rk62z-bash-5.2p26.drv»
```

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@ -13,3 +13,5 @@ libcmd_LDFLAGS = $(EDITLINE_LIBS) $(LOWDOWN_LIBS) $(NIXDOC_LIBS) -pthread
libcmd_LIBS = libstore libutil libexpr libmain libfetchers libcmd_LIBS = libstore libutil libexpr libmain libfetchers
$(eval $(call install-file-in, $(buildprefix)$(d)/nix-cmd.pc, $(libdir)/pkgconfig, 0644)) $(eval $(call install-file-in, $(buildprefix)$(d)/nix-cmd.pc, $(libdir)/pkgconfig, 0644))
$(d)/repl.cc: $(d)/repl-overlays.nix.gen.hh

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@ -32,8 +32,13 @@ libcmd_headers = files(
'repl.hh', 'repl.hh',
) )
libcmd_generated_headers = [
gen_header.process('repl-overlays.nix', preserve_path_from: meson.current_source_dir()),
]
libcmd = library( libcmd = library(
'nixcmd', 'nixcmd',
libcmd_generated_headers,
libcmd_sources, libcmd_sources,
dependencies : [ dependencies : [
liblixutil, liblixutil,

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@ -0,0 +1,8 @@
info:
initial:
functions:
let final = builtins.foldl'
(prev: function: prev // (function info final prev))
initial
functions;
in final

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@ -30,6 +30,7 @@
#include "signals.hh" #include "signals.hh"
#include "print.hh" #include "print.hh"
#include "progress-bar.hh" #include "progress-bar.hh"
#include "gc-small-vector.hh"
#if HAVE_BOEHMGC #if HAVE_BOEHMGC
#define GC_INCLUDE_NEW #define GC_INCLUDE_NEW
@ -118,6 +119,45 @@ struct NixRepl
void evalString(std::string s, Value & v); void evalString(std::string s, Value & v);
void loadDebugTraceEnv(DebugTrace & dt); void loadDebugTraceEnv(DebugTrace & dt);
/**
* Load the `repl-overlays` and add the resulting AttrSet to the top-level
* bindings.
*/
void loadReplOverlays();
/**
* Get a list of each of the `repl-overlays` (parsed and evaluated).
*/
Value * replOverlays();
/**
* Get the Nix function that composes the `repl-overlays` together.
*/
Value * getReplOverlaysEvalFunction();
/**
* Cached return value of `getReplOverlaysEvalFunction`.
*
* Note: This is `shared_ptr` to avoid garbage collection.
*/
std::shared_ptr<Value *> replOverlaysEvalFunction =
std::allocate_shared<Value *>(traceable_allocator<Value *>(), nullptr);
/**
* Get the `info` AttrSet that's passed as the first argument to each
* of the `repl-overlays`.
*/
Value * replInitInfo();
/**
* Get the current top-level bindings as an AttrSet.
*/
Value * bindingsToAttrs();
/**
* Parse a file, evaluate its result, and force the resulting value.
*/
Value * evalFile(SourcePath & path);
void printValue(std::ostream & str, void printValue(std::ostream & str,
Value & v, Value & v,
unsigned int maxDepth = std::numeric_limits<unsigned int>::max()) unsigned int maxDepth = std::numeric_limits<unsigned int>::max())
@ -770,14 +810,114 @@ void NixRepl::loadFiles()
loadedFiles.clear(); loadedFiles.clear();
for (auto & i : old) { for (auto & i : old) {
notice("Loading '%1%'...", i); notice("Loading '%1%'...", Magenta(i));
loadFile(i); loadFile(i);
} }
for (auto & [i, what] : getValues()) { for (auto & [i, what] : getValues()) {
notice("Loading installable '%1%'...", what); notice("Loading installable '%1%'...", Magenta(what));
addAttrsToScope(*i); addAttrsToScope(*i);
} }
loadReplOverlays();
}
void NixRepl::loadReplOverlays()
{
if (!evalSettings.replOverlays) {
return;
}
notice("Loading '%1%'...", Magenta("repl-overlays"));
auto replInitFilesFunction = getReplOverlaysEvalFunction();
Value &newAttrs(*state->allocValue());
SmallValueVector<3> args = {replInitInfo(), bindingsToAttrs(), replOverlays()};
state->callFunction(
*replInitFilesFunction,
args.size(),
args.data(),
newAttrs,
replInitFilesFunction->determinePos(noPos)
);
addAttrsToScope(newAttrs);
}
Value * NixRepl::getReplOverlaysEvalFunction()
{
if (replOverlaysEvalFunction && *replOverlaysEvalFunction) {
return *replOverlaysEvalFunction;
}
auto evalReplInitFilesPath = CanonPath::root + "repl-overlays.nix";
*replOverlaysEvalFunction = state->allocValue();
auto code =
#include "repl-overlays.nix.gen.hh"
;
auto expr = state->parseExprFromString(
code,
SourcePath(evalReplInitFilesPath),
state->staticBaseEnv
);
state->eval(expr, **replOverlaysEvalFunction);
return *replOverlaysEvalFunction;
}
Value * NixRepl::replOverlays()
{
Value * replInits(state->allocValue());
state->mkList(*replInits, evalSettings.replOverlays.get().size());
Value ** replInitElems = replInits->listElems();
size_t i = 0;
for (auto path : evalSettings.replOverlays.get()) {
debug("Loading '%1%' path '%2%'...", "repl-overlays", path);
SourcePath sourcePath((CanonPath(path)));
auto replInit = evalFile(sourcePath);
if (!replInit->isLambda()) {
state->error<TypeError>(
"Expected `repl-overlays` to be a lambda but found %1%: %2%",
showType(*replInit),
ValuePrinter(*state, *replInit, errorPrintOptions)
)
.atPos(replInit->determinePos(noPos))
.debugThrow();
}
if (replInit->lambda.fun->hasFormals()
&& !replInit->lambda.fun->formals->ellipsis) {
state->error<TypeError>(
"Expected first argument of %1% to have %2% to allow future versions of Lix to add additional attributes to the argument",
"repl-overlays",
"..."
)
.atPos(replInit->determinePos(noPos))
.debugThrow();
}
replInitElems[i] = replInit;
i++;
}
return replInits;
}
Value * NixRepl::replInitInfo()
{
auto builder = state->buildBindings(2);
Value * currentSystem(state->allocValue());
currentSystem->mkString(evalSettings.getCurrentSystem());
builder.insert(state->symbols.create("currentSystem"), currentSystem);
Value * info(state->allocValue());
info->mkAttrs(builder.finish());
return info;
} }
@ -810,6 +950,18 @@ void NixRepl::addVarToScope(const Symbol name, Value & v)
varNames.emplace(state->symbols[name]); varNames.emplace(state->symbols[name]);
} }
Value * NixRepl::bindingsToAttrs()
{
auto builder = state->buildBindings(staticEnv->vars.size());
for (auto & [symbol, displacement] : staticEnv->vars) {
builder.insert(symbol, env->values[displacement]);
}
Value * attrs(state->allocValue());
attrs->mkAttrs(builder.finish());
return attrs;
}
Expr * NixRepl::parseString(std::string s) Expr * NixRepl::parseString(std::string s)
{ {
@ -824,6 +976,15 @@ void NixRepl::evalString(std::string s, Value & v)
state->forceValue(v, v.determinePos(noPos)); state->forceValue(v, v.determinePos(noPos));
} }
Value * NixRepl::evalFile(SourcePath & path)
{
auto expr = state->parseExprFromFile(path, staticEnv);
Value * result(state->allocValue());
expr->eval(*state, *env, *result);
state->forceValue(*result, result->determinePos(noPos));
return result;
}
std::unique_ptr<AbstractNixRepl> AbstractNixRepl::create( std::unique_ptr<AbstractNixRepl> AbstractNixRepl::create(
const SearchPath & searchPath, nix::ref<Store> store, ref<EvalState> state, const SearchPath & searchPath, nix::ref<Store> store, ref<EvalState> state,

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@ -125,6 +125,42 @@ struct EvalSettings : Config
This is useful for debugging warnings in third-party Nix code. This is useful for debugging warnings in third-party Nix code.
)"}; )"};
PathsSetting replOverlays{this, Paths(), "repl-overlays",
R"(
A list of files containing Nix expressions that can be used to add
default bindings to [`nix
repl`](@docroot@/command-ref/new-cli/nix3-repl.md) sessions.
Each file is called with three arguments:
1. An [attribute set](@docroot@/language/values.html#attribute-set)
containing at least a
[`currentSystem`](@docroot@/language/builtin-constants.md#builtins-currentSystem)
attribute (this is identical to
[`builtins.currentSystem`](@docroot@/language/builtin-constants.md#builtins-currentSystem),
except that it's available in
[`pure-eval`](@docroot@/command-ref/conf-file.html#conf-pure-eval)
mode).
2. The top-level bindings produced by the previous `repl-overlays`
value (or the default top-level bindings).
3. The final top-level bindings produced by calling all
`repl-overlays`.
For example, the following file would alias `pkgs` to
`legacyPackages.${info.currentSystem}` (if that attribute is defined):
```nix
info: final: prev:
if prev ? legacyPackages
&& prev.legacyPackages ? ${info.currentSystem}
then
{
pkgs = prev.legacyPackages.${info.currentSystem};
}
else
{ }
```
)"};
}; };
extern EvalSettings evalSettings; extern EvalSettings evalSettings;

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@ -0,0 +1 @@
info: final: prev: builtins.abort "uh oh!"

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@ -0,0 +1,6 @@
let
puppy = "doggy";
in
{currentSystem}: final: prev: {
inherit puppy;
}

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@ -0,0 +1 @@
info: final: prev: {}

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@ -0,0 +1,4 @@
info: final: prev:
{
pkgs = final.packages.x86_64-linux;
}

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@ -0,0 +1,7 @@
info: final: prev:
{
var = prev.var + "b";
# We can access the final value of `var` here even though it isn't defined yet:
varUsingFinal = "final value is: " + final.newVar;
}

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@ -0,0 +1,6 @@
info: final: prev:
{
var = prev.var + "c";
newVar = "puppy";
}

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@ -0,0 +1,3 @@
{
packages.x86_64-linux.default = "my package";
}

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@ -0,0 +1,5 @@
Check basic `repl-overlays` functionality.
@args --repl-overlays
@args ${PWD}/extra_data/repl-overlay-packages-is-pkgs.nix
nix-repl> pkgs
{ default = "my package"; }

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@ -0,0 +1,3 @@
{
var = "a";
}

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@ -0,0 +1,7 @@
Check that multiple `repl-overlays` can compose together
@args --repl-overlays
@args "${PWD}/extra_data/repl-overlays-compose-1.nix ${PWD}/extra_data/repl-overlays-compose-2.nix"
nix-repl> var
"abc"
nix-repl> varUsingFinal
"final value is: puppy"

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@ -0,0 +1,10 @@
`repl-overlays` that try to parse out the `info` argument without a `...` error.
@args --repl-overlays
@args ${PWD}/extra_data/repl-overlay-no-dotdotdot.nix
@should-start false
error: Expected first argument of repl-overlays to have ... to allow future versions of Lix to add additional attributes to the argument
at $TEST_DATA/extra_data/repl-overlay-no-dotdotdot.nix:4:3:
3| in
4| {currentSystem}: final: prev: {
| ^
5| inherit puppy;\n

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@ -0,0 +1,5 @@
`repl-overlays` that don't destructure the `info` argument are OK.
@args --repl-overlays
@args ${PWD}/extra_data/repl-overlay-no-formals.nix
nix-repl> 1
1

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@ -0,0 +1,22 @@
`repl-overlays` that fail to evaluate should error.
@args --repl-overlays
@args ${PWD}/extra_data/repl-overlay-fail.nix
@should-start false
error:
… while calling the 'foldl'' builtin
at «string»:5:13:
4| functions:
5| let final = builtins.foldl'
| ^
6| (prev: function: prev // (function info final prev))
… in the right operand of the update (//) operator
at «string»:6:37:
5| let final = builtins.foldl'
6| (prev: function: prev // (function info final prev))
| ^
7| initial
(stack trace truncated; use '--show-trace' to show the full trace)
error: evaluation aborted with the following error message: 'uh oh!'

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@ -0,0 +1 @@
info: final: prev: builtins.abort "uh oh!"

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@ -0,0 +1 @@
{currentSystem}: final: prev: {}

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@ -0,0 +1,4 @@
info: final: prev:
{
pkgs = final.packages.x86_64-linux;
}

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@ -0,0 +1,7 @@
info: final: prev:
{
var = prev.var + "b";
# We can access the final value of `var` here even though it isn't defined yet:
varUsingFinal = "final value is: " + final.newVar;
}

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@ -0,0 +1,6 @@
info: final: prev:
{
var = prev.var + "c";
newVar = "puppy";
}

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@ -179,7 +179,12 @@ REPL_TEST(no_nested_debuggers);
REPL_TEST(regression_9917); REPL_TEST(regression_9917);
REPL_TEST(regression_9918); REPL_TEST(regression_9918);
REPL_TEST(regression_l145); REPL_TEST(regression_l145);
REPL_TEST(stack_vars); REPL_TEST(repl_overlays);
REPL_TEST(repl_overlays_compose);
REPL_TEST(repl_overlays_destructure_without_dotdotdot_errors);
REPL_TEST(repl_overlays_destructure_without_formals_ok);
REPL_TEST(repl_overlays_error);
REPL_TEST(repl_printing); REPL_TEST(repl_printing);
REPL_TEST(stack_vars);
}; // namespace nix }; // namespace nix