nrabulinski/lix
0
0
Fork 0
forked from lix-project/lix
Code Pull requests Activity

Merge pull request #8330 from NixOS/doc-auto-builtin-constants

Browse source 
Automatically document builtin constants
This commit is contained in:
John Ericson 2023-06-27 11:52:59 -04:00 committed by GitHub
parent 559fd7ffe7 22b278e011
commit 71d4fd8ebb
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
15 changed files with 463 additions and 158 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

3
.gitignore vendored
View file

@ -18,7 +18,7 @@ perl/Makefile.config
/doc/manual/generated/*
/doc/manual/nix.json
/doc/manual/conf-file.json
/doc/manual/builtins.json
/doc/manual/language.json
/doc/manual/xp-features.json
/doc/manual/src/SUMMARY.md
/doc/manual/src/command-ref/new-cli
@ -26,6 +26,7 @@ perl/Makefile.config
/doc/manual/src/command-ref/experimental-features-shortlist.md
/doc/manual/src/contributing/experimental-feature-descriptions.md
/doc/manual/src/language/builtins.md
/doc/manual/src/language/builtin-constants.md
# /scripts/
/scripts/nix-profile.sh

29
doc/manual/generate-builtin-constants.nix Normal file
View file

@ -0,0 +1,29 @@
let
inherit (builtins) concatStringsSep attrValues mapAttrs;
inherit (import ./utils.nix) optionalString squash;
in
builtinsInfo:
let
showBuiltin = name: { doc, type, impure-only }:
let
type' = optionalString (type != null) " (${type})";
impureNotice = optionalString impure-only ''
Not available in [pure evaluation mode](@docroot@/command-ref/conf-file.md#conf-pure-eval).
'';
in
squash ''
<dt id="builtin-constants-${name}">
<a href="#builtin-constants-${name}"><code>${name}</code>${type'}</a>
</dt>
<dd>
${doc}
${impureNotice}
</dd>
'';
in
concatStringsSep "\n" (attrValues (mapAttrs showBuiltin builtinsInfo))

16
doc/manual/generate-builtins.nix
View file

@ -1,14 +1,17 @@
let
inherit (builtins) concatStringsSep attrNames;
inherit (builtins) concatStringsSep attrValues mapAttrs;
inherit (import ./utils.nix) optionalString squash;
in
builtinsInfo:
let
showBuiltin = name:
showBuiltin = name: { doc, args, arity, experimental-feature }:
let
inherit (builtinsInfo.${name}) doc args;
experimentalNotice = optionalString (experimental-feature != null) ''
This function is only available if the [${experimental-feature}](@docroot@/contributing/experimental-features.md#xp-feature-${experimental-feature}) experimental feature is enabled.
'';
in
''
squash ''
<dt id="builtins-${name}">
<a href="#builtins-${name}"><code>${name} ${listArgs args}</code></a>
</dt>
@ -16,9 +19,10 @@ let
${doc}
${experimentalNotice}
</dd>
'';
listArgs = args: concatStringsSep " " (map (s: "<var>${s}</var>") args);
in
concatStringsSep "\n" (map showBuiltin (attrNames builtinsInfo))
concatStringsSep "\n" (attrValues (mapAttrs showBuiltin builtinsInfo))

16
doc/manual/local.mk
View file

@ -128,14 +128,20 @@ $(d)/xp-features.json: $(bindir)/nix
$(trace-gen) $(dummy-env) NIX_PATH=nix/corepkgs=corepkgs $(bindir)/nix __dump-xp-features > $@.tmp
@mv $@.tmp $@
$(d)/src/language/builtins.md: $(d)/builtins.json $(d)/generate-builtins.nix $(d)/src/language/builtins-prefix.md $(bindir)/nix
$(d)/src/language/builtins.md: $(d)/language.json $(d)/generate-builtins.nix $(d)/src/language/builtins-prefix.md $(bindir)/nix
@cat doc/manual/src/language/builtins-prefix.md > $@.tmp
$(trace-gen) $(nix-eval) --expr 'import doc/manual/generate-builtins.nix (builtins.fromJSON (builtins.readFile $<))' >> $@.tmp;
$(trace-gen) $(nix-eval) --expr 'import doc/manual/generate-builtins.nix (builtins.fromJSON (builtins.readFile $<)).builtins' >> $@.tmp;
@cat doc/manual/src/language/builtins-suffix.md >> $@.tmp
@mv $@.tmp $@
$(d)/builtins.json: $(bindir)/nix
$(trace-gen) $(dummy-env) NIX_PATH=nix/corepkgs=corepkgs $(bindir)/nix __dump-builtins > $@.tmp
$(d)/src/language/builtin-constants.md: $(d)/language.json $(d)/generate-builtin-constants.nix $(d)/src/language/builtin-constants-prefix.md $(bindir)/nix
@cat doc/manual/src/language/builtin-constants-prefix.md > $@.tmp
$(trace-gen) $(nix-eval) --expr 'import doc/manual/generate-builtin-constants.nix (builtins.fromJSON (builtins.readFile $<)).constants' >> $@.tmp;
@cat doc/manual/src/language/builtin-constants-suffix.md >> $@.tmp
@mv $@.tmp $@
$(d)/language.json: $(bindir)/nix
$(trace-gen) $(dummy-env) NIX_PATH=nix/corepkgs=corepkgs $(bindir)/nix __dump-language > $@.tmp
@mv $@.tmp $@
# Generate the HTML manual.
@ -167,7 +173,7 @@ doc/manual/generated/man1/nix3-manpages: $(d)/src/command-ref/new-cli
done
@touch $@
$(docdir)/manual/index.html: $(MANUAL_SRCS) $(d)/book.toml $(d)/anchors.jq $(d)/custom.css $(d)/src/SUMMARY.md $(d)/src/command-ref/new-cli $(d)/src/contributing/experimental-feature-descriptions.md $(d)/src/command-ref/conf-file.md $(d)/src/language/builtins.md
$(docdir)/manual/index.html: $(MANUAL_SRCS) $(d)/book.toml $(d)/anchors.jq $(d)/custom.css $(d)/src/SUMMARY.md $(d)/src/command-ref/new-cli $(d)/src/contributing/experimental-feature-descriptions.md $(d)/src/command-ref/conf-file.md $(d)/src/language/builtins.md $(d)/src/language/builtin-constants.md
$(trace-gen) \
tmp="$$(mktemp -d)"; \
cp -r doc/manual "$$tmp"; \

5
doc/manual/src/language/builtin-constants-prefix.md Normal file
View file

@ -0,0 +1,5 @@
# Built-in Constants
These constants are built into the Nix language evaluator:
<dl>

1
doc/manual/src/language/builtin-constants-suffix.md Normal file
View file

@ -0,0 +1 @@
</dl>

43
doc/manual/src/language/builtin-constants.md
View file

@ -1,43 +0,0 @@
# Built-in Constants
These constants are built into the Nix language evaluator:
- [`builtins`]{#builtins-builtins} (attribute set)
Contains all the [built-in functions](./builtins.md) and values, in order to avoid polluting the global scope.
Since built-in functions were added over time, [testing for attributes](./operators.md#has-attribute) in `builtins` can be used for graceful fallback on older Nix installations:
```nix
if builtins ? getEnv then builtins.getEnv "PATH" else ""
```
- [`builtins.currentSystem`]{#builtins-currentSystem} (string)
The built-in value `currentSystem` evaluates to the Nix platform
identifier for the Nix installation on which the expression is being
evaluated, such as `"i686-linux"` or `"x86_64-darwin"`.
Not available in [pure evaluation mode](@docroot@/command-ref/conf-file.md#conf-pure-eval).
- [`builtins.currentTime`]{#builtins-currentTime} (integer)
Return the [Unix time](https://en.wikipedia.org/wiki/Unix_time) at first evaluation.
Repeated references to that name will re-use the initially obtained value.
Example:
```console
$ nix repl
Welcome to Nix 2.15.1 Type :? for help.
nix-repl> builtins.currentTime
1683705525
nix-repl> builtins.currentTime
1683705525
```
The [store path](@docroot@/glossary.md#gloss-store-path) of a derivation depending on `currentTime` will differ for each evaluation.
Not available in [pure evaluation mode](@docroot@/command-ref/conf-file.md#conf-pure-eval).

58
src/libexpr/eval.cc
View file

@ -211,20 +211,21 @@ const Value * getPrimOp(const Value &v) {
return primOp;
}
std::string_view showType(ValueType type)
std::string_view showType(ValueType type, bool withArticle)
{
#define WA(a, w) withArticle ? a " " w : w
switch (type) {
case nInt: return "an integer";
case nBool: return "a Boolean";
case nString: return "a string";
case nPath: return "a path";
case nInt: return WA("an", "integer");
case nBool: return WA("a", "Boolean");
case nString: return WA("a", "string");
case nPath: return WA("a", "path");
case nNull: return "null";
case nAttrs: return "a set";
case nList: return "a list";
case nFunction: return "a function";
case nExternal: return "an external value";
case nFloat: return "a float";
case nThunk: return "a thunk";
case nAttrs: return WA("a", "set");
case nList: return WA("a", "list");
case nFunction: return WA("a", "function");
case nExternal: return WA("an", "external value");
case nFloat: return WA("a", "float");
case nThunk: return WA("a", "thunk");
}
abort();
}
@ -702,28 +703,34 @@ Path EvalState::toRealPath(const Path & path, const NixStringContext & context)
}
Value * EvalState::addConstant(const std::string & name, Value & v)
Value * EvalState::addConstant(const std::string & name, Value & v, Constant info)
{
Value * v2 = allocValue();
*v2 = v;
addConstant(name, v2);
addConstant(name, v2, info);
return v2;
}
void EvalState::addConstant(const std::string & name, Value * v)
void EvalState::addConstant(const std::string & name, Value * v, Constant info)
{
auto name2 = name.substr(0, 2) == "__" ? name.substr(2) : name;
constantInfos.push_back({name2, info});
if (!(evalSettings.pureEval && info.impureOnly)) {
/* Check the type, if possible.
We might know the type of a thunk in advance, so be allowed
to just write it down in that case. */
if (auto gotType = v->type(true); gotType != nThunk)
assert(info.type == gotType);
/* Install value the base environment. */
staticBaseEnv->vars.emplace_back(symbols.create(name), baseEnvDispl);
baseEnv.values[baseEnvDispl++] = v;
auto name2 = name.substr(0, 2) == "__" ? name.substr(2) : name;
baseEnv.values[0]->attrs->push_back(Attr(symbols.create(name2), v));
}
Value * EvalState::addPrimOp(const std::string & name,
size_t arity, PrimOpFun primOp)
{
return addPrimOp(PrimOp { .fun = primOp, .arity = arity, .name = name });
}
@ -737,7 +744,10 @@ Value * EvalState::addPrimOp(PrimOp && primOp)
vPrimOp->mkPrimOp(new PrimOp(primOp));
Value v;
v.mkApp(vPrimOp, vPrimOp);
return addConstant(primOp.name, v);
return addConstant(primOp.name, v, {
.type = nThunk, // FIXME
.doc = primOp.doc,
});
}
auto envName = symbols.create(primOp.name);
@ -763,13 +773,13 @@ std::optional<EvalState::Doc> EvalState::getDoc(Value & v)
{
if (v.isPrimOp()) {
auto v2 = &v;
if (v2->primOp->doc)
if (auto * doc = v2->primOp->doc)
return Doc {
.pos = {},
.name = v2->primOp->name,
.arity = v2->primOp->arity,
.args = v2->primOp->args,
.doc = v2->primOp->doc,
.doc = doc,
};
}
return {};

92
src/libexpr/eval.hh
View file

@ -25,15 +25,72 @@ struct DerivedPath;
enum RepairFlag : bool;
/**
* Function that implements a primop.
*/
typedef void (* PrimOpFun) (EvalState & state, const PosIdx pos, Value * * args, Value & v);
/**
* Info about a primitive operation, and its implementation
*/
struct PrimOp
{
PrimOpFun fun;
size_t arity;
/**
* Name of the primop. `__` prefix is treated specially.
*/
std::string name;
/**
* Names of the parameters of a primop, for primops that take a
* fixed number of arguments to be substituted for these parameters.
*/
std::vector<std::string> args;
/**
* Aritiy of the primop.
*
* If `args` is not empty, this field will be computed from that
* field instead, so it doesn't need to be manually set.
*/
size_t arity = 0;
/**
* Optional free-form documentation about the primop.
*/
const char * doc = nullptr;
/**
* Implementation of the primop.
*/
PrimOpFun fun;
/**
* Optional experimental for this to be gated on.
*/
std::optional<ExperimentalFeature> experimentalFeature;
};
/**
* Info about a constant
*/
struct Constant
{
/**
* Optional type of the constant (known since it is a fixed value).
*
* @todo we should use an enum for this.
*/
ValueType type = nThunk;
/**
* Optional free-form documentation about the constant.
*/
const char * doc = nullptr;
/**
* Whether the constant is impure, and not available in pure mode.
*/
bool impureOnly = false;
};
#if HAVE_BOEHMGC
@ -513,18 +570,23 @@ public:
*/
std::shared_ptr<StaticEnv> staticBaseEnv; // !!! should be private
/**
* Name and documentation about every constant.
*
* Constants from primops are hard to crawl, and their docs will go
* here too.
*/
std::vector<std::pair<std::string, Constant>> constantInfos;
private:
unsigned int baseEnvDispl = 0;
void createBaseEnv();
Value * addConstant(const std::string & name, Value & v);
Value * addConstant(const std::string & name, Value & v, Constant info);
void addConstant(const std::string & name, Value * v);
Value * addPrimOp(const std::string & name,
size_t arity, PrimOpFun primOp);
void addConstant(const std::string & name, Value * v, Constant info);
Value * addPrimOp(PrimOp && primOp);
@ -538,6 +600,10 @@ public:
std::optional<std::string> name;
size_t arity;
std::vector<std::string> args;
/**
* Unlike the other `doc` fields in this file, this one should never be
* `null`.
*/
const char * doc;
};
@ -704,8 +770,11 @@ struct DebugTraceStacker {
/**
* @return A string representing the type of the value `v`.
*
* @param withArticle Whether to begin with an english article, e.g. "an
* integer" vs "integer".
*/
std::string_view showType(ValueType type);
std::string_view showType(ValueType type, bool withArticle = true);
std::string showType(const Value & v);
/**
@ -737,7 +806,12 @@ struct EvalSettings : Config
Setting<Strings> nixPath{
this, getDefaultNixPath(), "nix-path",
"List of directories to be searched for `<...>` file references."};
R"(
List of directories to be searched for `<...>` file references
In particular, outside of [pure evaluation mode](#conf-pure-evaluation), this determines the value of
[`builtins.nixPath`](@docroot@/language/builtin-constants.md#builtin-constants-nixPath).
)"};
Setting<bool> restrictEval{
this, false, "restrict-eval",

3
src/libexpr/flake/flake.cc
View file

@ -788,9 +788,6 @@ static RegisterPrimOp r2({
```nix
(builtins.getFlake "github:edolstra/dwarffs").rev
```
This function is only available if you enable the experimental feature
`flakes`.
)",
.fun = prim_getFlake,
.experimentalFeature = Xp::Flakes,

283
src/libexpr/primops.cc
View file

@ -238,7 +238,7 @@ static void import(EvalState & state, const PosIdx pos, Value & vPath, Value * v
}
}
static RegisterPrimOp primop_scopedImport(RegisterPrimOp::Info {
static RegisterPrimOp primop_scopedImport(PrimOp {
.name = "scopedImport",
.arity = 2,
.fun = [](EvalState & state, const PosIdx pos, Value * * args, Value & v)
@ -692,7 +692,7 @@ static void prim_genericClosure(EvalState & state, const PosIdx pos, Value * * a
v.listElems()[n++] = i;
}
static RegisterPrimOp primop_genericClosure(RegisterPrimOp::Info {
static RegisterPrimOp primop_genericClosure(PrimOp {
.name = "__genericClosure",
.args = {"attrset"},
.arity = 1,
@ -809,7 +809,7 @@ static void prim_addErrorContext(EvalState & state, const PosIdx pos, Value * *
}
}
static RegisterPrimOp primop_addErrorContext(RegisterPrimOp::Info {
static RegisterPrimOp primop_addErrorContext(PrimOp {
.name = "__addErrorContext",
.arity = 2,
.fun = prim_addErrorContext,
@ -1400,7 +1400,7 @@ drvName, Bindings * attrs, Value & v)
v.mkAttrs(result);
}
static RegisterPrimOp primop_derivationStrict(RegisterPrimOp::Info {
static RegisterPrimOp primop_derivationStrict(PrimOp {
.name = "derivationStrict",
.arity = 1,
.fun = prim_derivationStrict,
@ -1667,9 +1667,52 @@ static void prim_findFile(EvalState & state, const PosIdx pos, Value * * args, V
v.mkPath(state.checkSourcePath(state.findFile(searchPath, path, pos)));
}
static RegisterPrimOp primop_findFile(RegisterPrimOp::Info {
static RegisterPrimOp primop_findFile(PrimOp {
.name = "__findFile",
.arity = 2,
.args = {"search path", "lookup path"},
.doc = R"(
Look up the given path with the given search path.
A search path is represented list of [attribute sets](./values.md#attribute-set) with two attributes, `prefix`, and `path`.
`prefix` is a relative path.
`path` denotes a file system location; the exact syntax depends on the command line interface.
Examples of search path attribute sets:
- ```
{
prefix = "nixos-config";
path = "/etc/nixos/configuration.nix";
}
```
- ```
{
prefix = "";
path = "/nix/var/nix/profiles/per-user/root/channels";
}
```
The lookup algorithm checks each entry until a match is found, returning a [path value](@docroot@/language/values.html#type-path) of the match.
This is the process for each entry:
If the lookup path matches `prefix`, then the remainder of the lookup path (the "suffix") is searched for within the directory denoted by `patch`.
Note that the `path` may need to be downloaded at this point to look inside.
If the suffix is found inside that directory, then the entry is a match;
the combined absolute path of the directory (now downloaded if need be) and the suffix is returned.
The syntax
```nix
<nixpkgs>
```
is equivalent to:
```nix
builtins.findFile builtins.nixPath "nixpkgs"
```
)",
.fun = prim_findFile,
});
@ -2388,7 +2431,7 @@ static void prim_unsafeGetAttrPos(EvalState & state, const PosIdx pos, Value * *
state.mkPos(v, i->pos);
}
static RegisterPrimOp primop_unsafeGetAttrPos(RegisterPrimOp::Info {
static RegisterPrimOp primop_unsafeGetAttrPos(PrimOp {
.name = "__unsafeGetAttrPos",
.arity = 2,
.fun = prim_unsafeGetAttrPos,
@ -4061,10 +4104,10 @@ static RegisterPrimOp primop_splitVersion({
RegisterPrimOp::PrimOps * RegisterPrimOp::primOps;
RegisterPrimOp::RegisterPrimOp(Info && info)
RegisterPrimOp::RegisterPrimOp(PrimOp && primOp)
{
if (!primOps) primOps = new PrimOps;
primOps->push_back(std::move(info));
primOps->push_back(std::move(primOp));
}
@ -4077,54 +4120,202 @@ void EvalState::createBaseEnv()
/* `builtins' must be first! */
v.mkAttrs(buildBindings(128).finish());
addConstant("builtins", v);
addConstant("builtins", v, {
.type = nAttrs,
.doc = R"(
Contains all the [built-in functions](@docroot@/language/builtins.md) and values.
Since built-in functions were added over time, [testing for attributes](./operators.md#has-attribute) in `builtins` can be used for graceful fallback on older Nix installations:
```nix
# if hasContext is not available, we assume `s` has a context
if builtins ? hasContext then builtins.hasContext s else true
```
)",
});
v.mkBool(true);
addConstant("true", v);
addConstant("true", v, {
.type = nBool,
.doc = R"(
Primitive value.
It can be returned by
[comparison operators](@docroot@/language/operators.md#Comparison)
and used in
[conditional expressions](@docroot@/language/constructs.md#Conditionals).
The name `true` is not special, and can be shadowed:
```nix-repl
nix-repl> let true = 1; in true
1
```
)",
});
v.mkBool(false);
addConstant("false", v);
addConstant("false", v, {
.type = nBool,
.doc = R"(
Primitive value.
It can be returned by
[comparison operators](@docroot@/language/operators.md#Comparison)
and used in
[conditional expressions](@docroot@/language/constructs.md#Conditionals).
The name `false` is not special, and can be shadowed:
```nix-repl
nix-repl> let false = 1; in false
1
```
)",
});
v.mkNull();
addConstant("null", v);
addConstant("null", v, {
.type = nNull,
.doc = R"(
Primitive value.
The name `null` is not special, and can be shadowed:
```nix-repl
nix-repl> let null = 1; in null
1
```
)",
});
if (!evalSettings.pureEval) {
v.mkInt(time(0));
addConstant("__currentTime", v);
v.mkString(settings.thisSystem.get());
addConstant("__currentSystem", v);
}
addConstant("__currentTime", v, {
.type = nInt,
.doc = R"(
Return the [Unix time](https://en.wikipedia.org/wiki/Unix_time) at first evaluation.
Repeated references to that name will re-use the initially obtained value.
Example:
```console
$ nix repl
Welcome to Nix 2.15.1 Type :? for help.
nix-repl> builtins.currentTime
1683705525
nix-repl> builtins.currentTime
1683705525
```
The [store path](@docroot@/glossary.md#gloss-store-path) of a derivation depending on `currentTime` will differ for each evaluation, unless both evaluate `builtins.currentTime` in the same second.
)",
.impureOnly = true,
});
if (!evalSettings.pureEval) {
v.mkString(settings.thisSystem.get());
}
addConstant("__currentSystem", v, {
.type = nString,
.doc = R"(
The value of the [`system` configuration option](@docroot@/command-ref/conf-file.md#conf-pure-eval).
It can be used to set the `system` attribute for [`builtins.derivation`](@docroot@/language/derivations.md) such that the resulting derivation can be built on the same system that evaluates the Nix expression:
```nix
builtins.derivation {
# ...
system = builtins.currentSystem;
}
```
It can be overridden in order to create derivations for different system than the current one:
```console
$ nix-instantiate --system "mips64-linux" --eval --expr 'builtins.currentSystem'
"mips64-linux"
```
)",
.impureOnly = true,
});
v.mkString(nixVersion);
addConstant("__nixVersion", v);
addConstant("__nixVersion", v, {
.type = nString,
.doc = R"(
The version of Nix.
For example, where the command line returns the current Nix version,
```shell-session
$ nix --version
nix (Nix) 2.16.0
```
the Nix language evaluator returns the same value:
```nix-repl
nix-repl> builtins.nixVersion
"2.16.0"
```
)",
});
v.mkString(store->storeDir);
addConstant("__storeDir", v);
addConstant("__storeDir", v, {
.type = nString,
.doc = R"(
Logical file system location of the [Nix store](@docroot@/glossary.md#gloss-store) currently in use.
This value is determined by the `store` parameter in [Store URLs](@docroot@/command-ref/new-cli/nix3-help-stores.md):
```shell-session
$ nix-instantiate --store 'dummy://?store=/blah' --eval --expr builtins.storeDir
"/blah"
```
)",
});
/* Language version. This should be increased every time a new
language feature gets added. It's not necessary to increase it
when primops get added, because you can just use `builtins ?
primOp' to check. */
v.mkInt(6);
addConstant("__langVersion", v);
addConstant("__langVersion", v, {
.type = nInt,
.doc = R"(
The current version of the Nix language.
)",
});
// Miscellaneous
if (evalSettings.enableNativeCode) {
addPrimOp("__importNative", 2, prim_importNative);
addPrimOp("__exec", 1, prim_exec);
addPrimOp({
.name = "__importNative",
.arity = 2,
.fun = prim_importNative,
});
addPrimOp({
.name = "__exec",
.arity = 1,
.fun = prim_exec,
});
}
addPrimOp({
.fun = evalSettings.traceVerbose ? prim_trace : prim_second,
.arity = 2,
.name = "__traceVerbose",
.args = { "e1", "e2" },
.arity = 2,
.doc = R"(
Evaluate *e1* and print its abstract syntax representation on standard
error if `--trace-verbose` is enabled. Then return *e2*. This function
is useful for debugging.
)",
.fun = evalSettings.traceVerbose ? prim_trace : prim_second,
});
/* Add a value containing the current Nix expression search path. */
@ -4136,26 +4327,46 @@ void EvalState::createBaseEnv()
attrs.alloc("prefix").mkString(i.prefix);
(v.listElems()[n++] = allocValue())->mkAttrs(attrs);
}
addConstant("__nixPath", v);
addConstant("__nixPath", v, {
.type = nList,
.doc = R"(
The search path used to resolve angle bracket path lookups.
Angle bracket expressions can be
[desugared](https://en.wikipedia.org/wiki/Syntactic_sugar)
using this and
[`builtins.findFile`](./builtins.html#builtins-findFile):
```nix
<nixpkgs>
```
is equivalent to:
```nix
builtins.findFile builtins.nixPath "nixpkgs"
```
)",
});
if (RegisterPrimOp::primOps)
for (auto & primOp : *RegisterPrimOp::primOps)
if (!primOp.experimentalFeature
|| experimentalFeatureSettings.isEnabled(*primOp.experimentalFeature))
if (experimentalFeatureSettings.isEnabled(primOp.experimentalFeature))
{
addPrimOp({
.fun = primOp.fun,
.arity = std::max(primOp.args.size(), primOp.arity),
.name = primOp.name,
.args = primOp.args,
.doc = primOp.doc,
});
auto primOpAdjusted = primOp;
primOpAdjusted.arity = std::max(primOp.args.size(), primOp.arity);
addPrimOp(std::move(primOpAdjusted));
}
/* Add a wrapper around the derivation primop that computes the
`drvPath' and `outPath' attributes lazily. */
`drvPath' and `outPath' attributes lazily.
Null docs because it is documented separately.
*/
auto vDerivation = allocValue();
addConstant("derivation", vDerivation);
addConstant("derivation", vDerivation, {
.type = nFunction,
});
/* Now that we've added all primops, sort the `builtins' set,
because attribute lookups expect it to be sorted. */

14
src/libexpr/primops.hh
View file

@ -10,17 +10,7 @@ namespace nix {
struct RegisterPrimOp
{
struct Info
{
std::string name;
std::vector<std::string> args;
size_t arity = 0;
const char * doc;
PrimOpFun fun;
std::optional<ExperimentalFeature> experimentalFeature;
};
typedef std::vector<Info> PrimOps;
typedef std::vector<PrimOp> PrimOps;
static PrimOps * primOps;
/**
@ -28,7 +18,7 @@ struct RegisterPrimOp
* will get called during EvalState initialization, so there
* may be primops not yet added and builtins is not yet sorted.
*/
RegisterPrimOp(Info && info);
RegisterPrimOp(PrimOp && primOp);
};
/* These primops are disabled without enableNativeCode, but plugins

3
src/libexpr/primops/fetchClosure.cc
View file

@ -154,9 +154,6 @@ static RegisterPrimOp primop_fetchClosure({
specifying a binary cache from which the path can be fetched.
Also, requiring a content-addressed final store path avoids the
need for users to configure binary cache public keys.
This function is only available if you enable the experimental
feature `fetch-closure`.
)",
.fun = prim_fetchClosure,
.experimentalFeature = Xp::FetchClosure,

8
src/libexpr/value.hh
View file

@ -218,8 +218,11 @@ public:
/**
* Returns the normal type of a Value. This only returns nThunk if
* the Value hasn't been forceValue'd
*
* @param invalidIsThunk Instead of aborting an an invalid (probably
* 0, so uninitialized) internal type, return `nThunk`.
*/
inline ValueType type() const
inline ValueType type(bool invalidIsThunk = false) const
{
switch (internalType) {
case tInt: return nInt;
@ -234,6 +237,9 @@ public:
case tFloat: return nFloat;
case tThunk: case tApp: case tBlackhole: return nThunk;
}
if (invalidIsThunk)
return nThunk;
else
abort();
}

21
src/nix/main.cc
View file

@ -352,7 +352,7 @@ void mainWrapped(int argc, char * * argv)
return;
}
if (argc == 2 && std::string(argv[1]) == "__dump-builtins") {
if (argc == 2 && std::string(argv[1]) == "__dump-language") {
experimentalFeatureSettings.experimentalFeatures = {
Xp::Flakes,
Xp::FetchClosure,
@ -360,6 +360,8 @@ void mainWrapped(int argc, char * * argv)
evalSettings.pureEval = false;
EvalState state({}, openStore("dummy://"));
auto res = nlohmann::json::object();
res["builtins"] = ({
auto builtinsJson = nlohmann::json::object();
auto builtins = state.baseEnv.values[0]->attrs;
for (auto & builtin : *builtins) {
auto b = nlohmann::json::object();
@ -369,8 +371,23 @@ void mainWrapped(int argc, char * * argv)
b["arity"] = primOp->arity;
b["args"] = primOp->args;
b["doc"] = trim(stripIndentation(primOp->doc));
res[state.symbols[builtin.name]] = std::move(b);
b["experimental-feature"] = primOp->experimentalFeature;
builtinsJson[state.symbols[builtin.name]] = std::move(b);
}
std::move(builtinsJson);
});
res["constants"] = ({
auto constantsJson = nlohmann::json::object();
for (auto & [name, info] : state.constantInfos) {
auto c = nlohmann::json::object();
if (!info.doc) continue;
c["doc"] = trim(stripIndentation(info.doc));
c["type"] = showType(info.type, false);
c["impure-only"] = info.impureOnly;
constantsJson[name] = std::move(c);
}
std::move(constantsJson);
});
logger->cout("%s", res);
return;
}