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* Big cleanup of the semantics of paths, strings, contexts, string

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concatenation and string coercion.  This was a big mess (see
  e.g. NIX-67).  Contexts are now folded into strings, so that they
  don't cause evaluation errors when they're not expected.  The
  semantics of paths has been clarified (see nixexpr-ast.def).
  toString() and coerceToString() have been merged.

  Semantic change: paths are now copied to the store when they're in a
  concatenation (and in most other situations - that's the
  formalisation of the meaning of a path).  So

    "foo " + ./bla

  evaluates to "foo /nix/store/hash...-bla", not "foo
  /path/to/current-dir/bla".  This prevents accidental impurities, and
  is more consistent with the treatment of derivation outputs, e.g.,
  `"foo " + bla' where `bla' is a derivation.  (Here `bla' would be
  replaced by the output path of `bla'.)
This commit is contained in:
Eelco Dolstra 2006-10-16 15:55:34 +00:00
parent 4c9aa821b9
commit d7efd76394
17 changed files with 331 additions and 396 deletions
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4
src/libexpr/parser.y
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@ -195,12 +195,12 @@ expr_simple
| INT { $$ = makeInt(ATgetInt((ATermInt) $1)); }
| '"' string_parts '"' {
/* For efficiency, and to simplify parse trees a bit. */
if ($2 == ATempty) $$ = makeStr(toATerm(""));
if ($2 == ATempty) $$ = makeStr(toATerm(""), ATempty);
else if (ATgetNext($2) == ATempty) $$ = ATgetFirst($2);
else $$ = makeConcatStrings(ATreverse($2));
}
| PATH { $$ = makePath(toATerm(absPath(aterm2String($1), data->basePath))); }
| URI { $$ = makeStr($1); }
| URI { $$ = makeStr($1, ATempty); }
| '(' expr ')' { $$ = $2; }
/* Let expressions `let {..., body = ...}' are just desugared
into `(rec {..., body = ...}).body'. */