diff options
| -rw-r--r-- | src/libexpr/primops.cc | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc index 13565b950..1d1afa768 100644 --- a/src/libexpr/primops.cc +++ b/src/libexpr/primops.cc @@ -696,10 +696,14 @@ static RegisterPrimOp primop_tryEval({ Try to shallowly evaluate *e*. Return a set containing the attributes `success` (`true` if *e* evaluated successfully, `false` if an error was thrown) and `value`, equalling *e* if - successful and `false` otherwise. Note that this doesn't evaluate - *e* deeply, so ` let e = { x = throw ""; }; in (builtins.tryEval - e).success ` will be `true`. Using ` builtins.deepSeq ` one can - get the expected result: `let e = { x = throw ""; }; in + successful and `false` otherwise. `tryEval` will only prevent + errors created by `throw` or `assert` from being thrown. + Errors `tryEval` will not catch are for example those created + by `abort` and type errors generated by builtins. Also note that + this doesn't evaluate *e* deeply, so `let e = { x = throw ""; }; + in (builtins.tryEval e).success` will be `true`. Using + `builtins.deepSeq` one can get the expected result: + `let e = { x = throw ""; }; in (builtins.tryEval (builtins.deepSeq e e)).success` will be `false`. )", |