nixpkgs/lib/debug.nix

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Nix
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Convert libs to a fixed-point This does break the API of being able to import any lib file and get its libs, however I'm not sure people did this. I made this while exploring being able to swap out docFn with a stub in #2305, to avoid functor performance problems. I don't know if that is going to move forward (or if it is a problem or not,) but after doing all this work figured I'd put it up anyway :) Two notable advantages to this approach: 1. when a lib inherits another lib's functions, it doesn't automatically get put in to the scope of lib 2. when a lib implements a new obscure functions, it doesn't automatically get put in to the scope of lib Using the test script (later in this commit) I got the following diff on the API: + diff master fixed-lib 11764a11765,11766 > .types.defaultFunctor > .types.defaultTypeMerge 11774a11777,11778 > .types.isOptionType > .types.isType 11781a11786 > .types.mkOptionType 11788a11794 > .types.setType 11795a11802 > .types.types This means that this commit _adds_ to the API, however I can't find a way to fix these last remaining discrepancies. At least none are _removed_. Test script (run with nix-repl in the PATH): #!/bin/sh set -eux repl() { suff=${1:-} echo "(import ./lib)$suff" \ | nix-repl 2>&1 } attrs_to_check() { repl "${1:-}" \ | tr ';' $'\n' \ | grep "\.\.\." \ | cut -d' ' -f2 \ | sed -e "s/^/${1:-}./" \ | sort } summ() { repl "${1:-}" \ | tr ' ' $'\n' \ | sort \ | uniq } deep_summ() { suff="${1:-}" depth="${2:-4}" depth=$((depth - 1)) summ "$suff" for attr in $(attrs_to_check "$suff" | grep -v "types.types"); do if [ $depth -eq 0 ]; then summ "$attr" | sed -e "s/^/$attr./" else deep_summ "$attr" "$depth" | sed -e "s/^/$attr./" fi done } ( cd nixpkgs #git add . #git commit -m "Auto-commit, sorry" || true git checkout fixed-lib deep_summ > ../fixed-lib git checkout master deep_summ > ../master ) if diff master fixed-lib; then echo "SHALLOW MATCH!" fi ( cd nixpkgs git checkout fixed-lib repl .types )
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{ lib }:
let
inherit (builtins) trace attrNamesToStr isAttrs isFunction isList isInt
isString isBool head substring attrNames;
inherit (lib) all id mapAttrsFlatten elem;
in
rec {
inherit (builtins) addErrorContext;
addErrorContextToAttrs = lib.mapAttrs (a: v: lib.addErrorContext "while evaluating ${a}" v);
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traceIf = p: msg: x: if p then trace msg x else x;
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traceVal = x: trace x x;
traceXMLVal = x: trace (builtins.toXML x) x;
traceXMLValMarked = str: x: trace (str + builtins.toXML x) x;
# strict trace functions (traced structure is fully evaluated and printed)
/* `builtins.trace`, but the value is `builtins.deepSeq`ed first. */
traceSeq = x: y: trace (builtins.deepSeq x x) y;
/* Like `traceSeq`, but only down to depth n.
* This is very useful because lots of `traceSeq` usages
* lead to an infinite recursion.
*/
traceSeqN = depth: x: y: with lib;
let snip = v: if isList v then noQuotes "[]" v
else if isAttrs v then noQuotes "{}" v
else v;
noQuotes = str: v: { __pretty = const str; val = v; };
modify = n: fn: v: if (n == 0) then fn v
else if isList v then map (modify (n - 1) fn) v
else if isAttrs v then mapAttrs
(const (modify (n - 1) fn)) v
else v;
in trace (generators.toPretty { allowPrettyValues = true; }
(modify depth snip x)) y;
/* `traceSeq`, but the same value is traced and returned */
traceValSeq = v: traceVal (builtins.deepSeq v v);
/* `traceValSeq` but with fixed depth */
traceValSeqN = depth: v: traceSeqN depth v v;
# this can help debug your code as well - designed to not produce thousands of lines
traceShowVal = x: trace (showVal x) x;
traceShowValMarked = str: x: trace (str + showVal x) x;
attrNamesToStr = a: lib.concatStringsSep "; " (map (x: "${x}=") (attrNames a));
showVal = x:
if isAttrs x then
if x ? outPath then "x is a derivation, name ${if x ? name then x.name else "<no name>"}, { ${attrNamesToStr x} }"
else "x is attr set { ${attrNamesToStr x} }"
else if isFunction x then "x is a function"
else if x == [] then "x is an empty list"
else if isList x then "x is a list, first element is: ${showVal (head x)}"
else if x == true then "x is boolean true"
else if x == false then "x is boolean false"
else if x == null then "x is null"
else if isInt x then "x is an integer `${toString x}'"
else if isString x then "x is a string `${substring 0 50 x}...'"
else "x is probably a path `${substring 0 50 (toString x)}...'";
# trace the arguments passed to function and its result
# maybe rewrite these functions in a traceCallXml like style. Then one function is enough
traceCall = n: f: a: let t = n2: x: traceShowValMarked "${n} ${n2}:" x; in t "result" (f (t "arg 1" a));
traceCall2 = n: f: a: b: let t = n2: x: traceShowValMarked "${n} ${n2}:" x; in t "result" (f (t "arg 1" a) (t "arg 2" b));
traceCall3 = n: f: a: b: c: let t = n2: x: traceShowValMarked "${n} ${n2}:" x; in t "result" (f (t "arg 1" a) (t "arg 2" b) (t "arg 3" c));
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# FIXME: rename this?
traceValIfNot = c: x:
if c x then true else trace (showVal x) false;
/* Evaluate a set of tests. A test is an attribute set {expr,
expected}, denoting an expression and its expected result. The
result is a list of failed tests, each represented as {name,
expected, actual}, denoting the attribute name of the failing
test and its expected and actual results. Used for regression
testing of the functions in lib; see tests.nix for an example.
Only tests having names starting with "test" are run.
Add attr { tests = ["testName"]; } to run these test only
*/
runTests = tests: lib.concatLists (lib.attrValues (lib.mapAttrs (name: test:
let testsToRun = if tests ? tests then tests.tests else [];
in if (substring 0 4 name == "test" || elem name testsToRun)
&& ((testsToRun == []) || elem name tests.tests)
&& (test.expr != test.expected)
then [ { inherit name; expected = test.expected; result = test.expr; } ]
else [] ) tests));
# create a test assuming that list elements are true
# usage: { testX = allTrue [ true ]; }
testAllTrue = expr: { inherit expr; expected = map (x: true) expr; };
strict = v:
trace "Warning: strict is deprecated and will be removed in the next release"
(builtins.seq v v);
# example: (traceCallXml "myfun" id 3) will output something like
# calling myfun arg 1: 3 result: 3
# this forces deep evaluation of all arguments and the result!
# note: if result doesn't evaluate you'll get no trace at all (FIXME)
# args should be printed in any case
traceCallXml = a:
if !isInt a then
traceCallXml 1 "calling ${a}\n"
else
let nr = a;
in (str: expr:
if isFunction expr then
(arg:
traceCallXml (builtins.add 1 nr) "${str}\n arg ${builtins.toString nr} is \n ${builtins.toXML (strict arg)}" (expr arg)
)
else
let r = strict expr;
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in trace "${str}\n result:\n${builtins.toXML r}" r
);
}