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* Added an experimental feature suggested by Andres: ellipses ("...")
in attribute set pattern matches. This allows defining a function
that takes *at least* the listed attributes, while ignoring
additional attributes. For instance,
{stdenv, fetchurl, fuse, ...}:
stdenv.mkDerivation {
...
};
defines a function that requires an attribute set that contains the
specified attributes but ignores others. The main advantage is that
we can then write in all-packages.nix
aefs = import ../bla/aefs pkgs;
instead of
aefs = import ../bla/aefs {
inherit stdenv fetchurl fuse;
};
This saves a lot of typing (not to mention not having to update
all-packages.nix with purely mechanical changes). It saves as much
typing as the "args: with args;" style, but has the advantage that
the function arguments are properly declared (not implicit in what
the body of the "with" uses).
This commit is contained in:
Eelco Dolstra
parent
db4f4a8425
commit
9279174dde
@ -84,11 +84,12 @@ static void patternMatch(EvalState & state,
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ATerm name;
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ATermList formals;
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Pattern pat1, pat2;
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ATermBool ellipsis;
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if (matchVarPat(pat, name))
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subs.set(name, arg);
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else if (matchAttrsPat(pat, formals)) {
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else if (matchAttrsPat(pat, formals, ellipsis)) {
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arg = evalExpr(state, arg);
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@ -122,8 +123,8 @@ static void patternMatch(EvalState & state,
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}
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/* Check that each actual argument is listed as a formal
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argument. */
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if (attrsUsed != nrAttrs)
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argument (unless the attribute match specifies a `...'). */
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if (ellipsis == eFalse && attrsUsed != nrAttrs)
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throw TypeError(format("the function does not expect an argument named `%1%'")
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% aterm2String(attrs.begin()->key));
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}
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@ -402,9 +403,10 @@ Expr autoCallFunction(Expr e, const ATermMap & args)
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Pattern pat;
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ATerm body, pos;
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ATermList formals;
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ATermBool ellipsis;
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/* !!! this should be more general */
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if (matchFunction(e, pat, body, pos) && matchAttrsPat(pat, formals)) {
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if (matchFunction(e, pat, body, pos) && matchAttrsPat(pat, formals, ellipsis)) {
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ATermMap actualArgs(ATgetLength(formals));
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for (ATermIterator i(formals); i; ++i) {
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@ -45,15 +45,17 @@ static void printPatternAsXML(Pattern pat, XMLWriter & doc)
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ATerm name;
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ATermList formals;
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Pattern pat1, pat2;
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ATermBool ellipsis;
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if (matchVarPat(pat, name))
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doc.writeEmptyElement("varpat", singletonAttrs("name", aterm2String(name)));
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else if (matchAttrsPat(pat, formals)) {
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else if (matchAttrsPat(pat, formals, ellipsis)) {
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XMLOpenElement _(doc, "attrspat");
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for (ATermIterator i(formals); i; ++i) {
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Expr name; ATerm dummy;
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if (!matchFormal(*i, name, dummy)) abort();
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doc.writeEmptyElement("attr", singletonAttrs("name", aterm2String(name)));
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}
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if (ellipsis == eTrue) doc.writeEmptyElement("ellipsis");
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}
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else if (matchAtPat(pat, pat1, pat2)) {
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XMLOpenElement _(doc, "at");
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@ -95,6 +95,7 @@ let { return LET; }
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in { return IN; }
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rec { return REC; }
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inherit { return INHERIT; }
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\.\.\. { return ELLIPSIS; }
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\=\= { return EQ; }
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\!\= { return NEQ; }
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@ -66,7 +66,7 @@ PrimOp | int ATermBlob ATermList | Expr |
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Attrs | ATermList | Expr |
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Closed | Expr | Expr |
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Rec | ATermList ATermList | Expr |
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Bool | ATerm | Expr |
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Bool | ATermBool | Expr |
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Null | | Expr |
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Bind | string Expr Pos | ATerm |
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@ -76,7 +76,7 @@ Inherit | Expr ATermList Pos | ATerm |
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Scope | | Expr |
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VarPat | string | Pattern |
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AttrsPat | ATermList | Pattern |
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AttrsPat | ATermList ATermBool | Pattern | # bool = `...'
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AtPat | Pattern Pattern | Pattern |
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Formal | string DefaultValue | ATerm |
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@ -84,8 +84,8 @@ Formal | string DefaultValue | ATerm |
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DefaultValue | Expr | DefaultValue |
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NoDefaultValue | | DefaultValue |
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True | | ATerm |
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False | | ATerm |
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True | | ATermBool |
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False | | ATermBool |
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PrimOpDef | int ATermBlob | ATerm |
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@ -115,11 +115,12 @@ static void varsBoundByPattern(ATermMap & map, Pattern pat)
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ATerm name;
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ATermList formals;
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Pattern pat1, pat2;
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ATermBool ellipsis;
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/* Use makeRemoved() so that it can be used directly in
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substitute(). */
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if (matchVarPat(pat, name))
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map.set(name, makeRemoved());
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else if (matchAttrsPat(pat, formals)) {
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else if (matchAttrsPat(pat, formals, ellipsis)) {
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for (ATermIterator i(formals); i; ++i) {
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ATerm d1;
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if (!matchFormal(*i, name, d1)) abort();
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@ -24,6 +24,7 @@ typedef ATerm Expr;
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typedef ATerm DefaultValue;
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typedef ATerm Pos;
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typedef ATerm Pattern;
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typedef ATerm ATermBool;
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/* A STL vector of ATerms. Should be used with great care since it's
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@ -208,16 +208,22 @@ static void freeAndUnprotect(void * p)
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%union {
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ATerm t;
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ATermList ts;
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struct {
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ATermList formals;
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bool ellipsis;
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} formals;
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}
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%type <t> start expr expr_function expr_if expr_op
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%type <t> expr_app expr_select expr_simple bind inheritsrc formal
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%type <t> pattern pattern2
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%type <ts> binds ids expr_list formals string_parts ind_string_parts
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%type <ts> binds ids expr_list string_parts ind_string_parts
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%type <formals> formals
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%token <t> ID INT STR IND_STR PATH URI
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%token IF THEN ELSE ASSERT WITH LET IN REC INHERIT EQ NEQ AND OR IMPL
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%token DOLLAR_CURLY /* == ${ */
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%token IND_STRING_OPEN IND_STRING_CLOSE
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%token ELLIPSIS
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%nonassoc IMPL
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%left OR
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@ -326,7 +332,7 @@ pattern
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pattern2
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: ID { $$ = makeVarPat($1); }
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| '{' formals '}' { $$ = makeAttrsPat($2); }
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| '{' formals '}' { $$ = makeAttrsPat($2.formals, $2.ellipsis ? eTrue : eFalse); }
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;
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binds
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@ -357,9 +363,14 @@ expr_list
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;
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formals
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: formal ',' formals { $$ = ATinsert($3, $1); } /* idem - right recursive */
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| formal { $$ = ATinsert(ATempty, $1); }
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| { $$ = ATempty; }
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: formal ',' formals /* idem - right recursive */
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{ $$.formals = ATinsert($3.formals, $1); $$.ellipsis = $3.ellipsis; }
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| formal
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{ $$.formals = ATinsert(ATempty, $1); $$.ellipsis = false; }
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{ $$.formals = ATempty; $$.ellipsis = false; }
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| ELLIPSIS
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{ $$.formals = ATempty; $$.ellipsis = true; }
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;
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formal
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@ -401,13 +412,14 @@ static void checkPatternVars(ATerm pos, ATermMap & map, Pattern pat)
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ATerm name;
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ATermList formals;
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Pattern pat1, pat2;
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ATermBool ellipsis;
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if (matchVarPat(pat, name)) {
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if (map.get(name))
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throw EvalError(format("duplicate formal function argument `%1%' at %2%")
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% aterm2String(name) % showPos(pos));
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map.set(name, name);
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}
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else if (matchAttrsPat(pat, formals)) {
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else if (matchAttrsPat(pat, formals, ellipsis)) {
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for (ATermIterator i(formals); i; ++i) {
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ATerm d1;
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if (!matchFormal(*i, name, d1)) abort();
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@ -1 +1 @@
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Str("abcxyzDDDDEFgh",[])
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Str("abcxyzDDDDEFghijk",[])
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@ -8,9 +8,12 @@ let
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i = args@args2: args.x + args2.y;
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j = {x, y, z, ...}: x + y + z;
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in
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f {x = "a"; y = "b"; z = "c";} +
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g {x = "x"; y = "y"; z = "z";} +
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h {x = "D";} +
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h {x = "D"; y = "E"; z = "F";} +
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i {x = "g"; y = "h";}
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i {x = "g"; y = "h";} +
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j {x = "i"; y = "j"; z = "k"; bla = "bla"; foo = "bar";}
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@ -22,6 +22,16 @@
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<attr name="c">
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<string value="foobar" />
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</attr>
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<attr name="ellipsis">
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<function>
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<attrspat>
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<attr name="x" />
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<attr name="y" />
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<attr name="z" />
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<ellipsis />
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</attrspat>
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</function>
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</attr>
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<attr name="f">
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<function>
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<attrspat>
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@ -14,4 +14,6 @@ rec {
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at = args@{x, y, z}: x;
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ellipsis = {x, y, z, ...}: x;
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}
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@ -1 +1 @@
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Function(AttrsPat([Formal("x",NoDefaultValue),Formal("y",NoDefaultValue),Formal("z",NoDefaultValue)]),OpPlus(OpPlus(Var("x"),Var("y")),Var("z")),NoPos)
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Function(AttrsPat([Formal("x",NoDefaultValue),Formal("y",NoDefaultValue),Formal("z",NoDefaultValue)],Bool(False)),OpPlus(OpPlus(Var("x"),Var("y")),Var("z")),NoPos)
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@ -1 +1 @@
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Function(AttrsPat([Formal("stdenv",NoDefaultValue),Formal("fetchurl",NoDefaultValue)]),Call(Select(Var("stdenv"),"mkDerivation"),Attrs([Bind("name",Str("libXi-6.0.1",[]),NoPos),Bind("src",Call(Var("fetchurl"),Attrs([Bind("md5",Str("7e935a42428d63a387b3c048be0f2756",[]),NoPos),Bind("url",Str("http://freedesktop.org/~xlibs/release/libXi-6.0.1.tar.bz2",[]),NoPos)])),NoPos)])),NoPos)
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Function(AttrsPat([Formal("stdenv",NoDefaultValue),Formal("fetchurl",NoDefaultValue)],Bool(False)),Call(Select(Var("stdenv"),"mkDerivation"),Attrs([Bind("name",Str("libXi-6.0.1",[]),NoPos),Bind("src",Call(Var("fetchurl"),Attrs([Bind("md5",Str("7e935a42428d63a387b3c048be0f2756",[]),NoPos),Bind("url",Str("http://freedesktop.org/~xlibs/release/libXi-6.0.1.tar.bz2",[]),NoPos)])),NoPos)])),NoPos)
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@ -1 +1 @@
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Function(AttrsPat([Formal("localServer",DefaultValue(Var("false"))),Formal("httpServer",DefaultValue(Var("false"))),Formal("sslSupport",DefaultValue(Var("false"))),Formal("pythonBindings",DefaultValue(Var("false"))),Formal("javaSwigBindings",DefaultValue(Var("false"))),Formal("javahlBindings",DefaultValue(Var("false"))),Formal("stdenv",NoDefaultValue),Formal("fetchurl",NoDefaultValue),Formal("openssl",DefaultValue(Var("null"))),Formal("httpd",DefaultValue(Var("null"))),Formal("db4",DefaultValue(Var("null"))),Formal("expat",NoDefaultValue),Formal("swig",DefaultValue(Var("null"))),Formal("j2sdk",DefaultValue(Var("null")))]),Assert(OpNEq(Var("expat"),Var("null")),Assert(OpImpl(Var("localServer"),OpNEq(Var("db4"),Var("null"))),Assert(OpImpl(Var("httpServer"),OpAnd(OpNEq(Var("httpd"),Var("null")),OpEq(Select(Var("httpd"),"expat"),Var("expat")))),Assert(OpImpl(Var("sslSupport"),OpAnd(OpNEq(Var("openssl"),Var("null")),OpImpl(Var("httpServer"),OpEq(Select(Var("httpd"),"openssl"),Var("openssl"))))),Assert(OpImpl(Var("pythonBindings"),OpAnd(OpNEq(Var("swig"),Var("null")),Select(Var("swig"),"pythonSupport"))),Assert(OpImpl(Var("javaSwigBindings"),OpAnd(OpNEq(Var("swig"),Var("null")),Select(Var("swig"),"javaSupport"))),Assert(OpImpl(Var("javahlBindings"),OpNEq(Var("j2sdk"),Var("null"))),Call(Select(Var("stdenv"),"mkDerivation"),Attrs([Bind("builder",Path("/foo/bar"),NoPos),Bind("db4",If(Var("localServer"),Var("db4"),Var("null")),NoPos),Bind("expat",Var("expat"),NoPos),Bind("httpServer",Var("httpServer"),NoPos),Bind("httpd",If(Var("httpServer"),Var("httpd"),Var("null")),NoPos),Bind("j2sdk",If(Var("javaSwigBindings"),Select(Var("swig"),"j2sdk"),If(Var("javahlBindings"),Var("j2sdk"),Var("null"))),NoPos),Bind("javaSwigBindings",Var("javaSwigBindings"),NoPos),Bind("javahlBindings",Var("javahlBindings"),NoPos),Bind("localServer",Var("localServer"),NoPos),Bind("name",Str("subversion-1.1.1",[]),NoPos),Bind("openssl",If(Var("sslSupport"),Var("openssl"),Var("null")),NoPos),Bind("patches",If(Var("javahlBindings"),List([Path("/javahl.patch")]),List([])),NoPos),Bind("python",If(Var("pythonBindings"),Select(Var("swig"),"python"),Var("null")),NoPos),Bind("pythonBindings",Var("pythonBindings"),NoPos),Bind("src",Call(Var("fetchurl"),Attrs([Bind("md5",Str("a180c3fe91680389c210c99def54d9e0",[]),NoPos),Bind("url",Str("http://subversion.tigris.org/tarballs/subversion-1.1.1.tar.bz2",[]),NoPos)])),NoPos),Bind("sslSupport",Var("sslSupport"),NoPos),Bind("swig",If(OpOr(Var("pythonBindings"),Var("javaSwigBindings")),Var("swig"),Var("null")),NoPos)])),NoPos),NoPos),NoPos),NoPos),NoPos),NoPos),NoPos),NoPos)
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Function(AttrsPat([Formal("localServer",DefaultValue(Var("false"))),Formal("httpServer",DefaultValue(Var("false"))),Formal("sslSupport",DefaultValue(Var("false"))),Formal("pythonBindings",DefaultValue(Var("false"))),Formal("javaSwigBindings",DefaultValue(Var("false"))),Formal("javahlBindings",DefaultValue(Var("false"))),Formal("stdenv",NoDefaultValue),Formal("fetchurl",NoDefaultValue),Formal("openssl",DefaultValue(Var("null"))),Formal("httpd",DefaultValue(Var("null"))),Formal("db4",DefaultValue(Var("null"))),Formal("expat",NoDefaultValue),Formal("swig",DefaultValue(Var("null"))),Formal("j2sdk",DefaultValue(Var("null")))],Bool(False)),Assert(OpNEq(Var("expat"),Var("null")),Assert(OpImpl(Var("localServer"),OpNEq(Var("db4"),Var("null"))),Assert(OpImpl(Var("httpServer"),OpAnd(OpNEq(Var("httpd"),Var("null")),OpEq(Select(Var("httpd"),"expat"),Var("expat")))),Assert(OpImpl(Var("sslSupport"),OpAnd(OpNEq(Var("openssl"),Var("null")),OpImpl(Var("httpServer"),OpEq(Select(Var("httpd"),"openssl"),Var("openssl"))))),Assert(OpImpl(Var("pythonBindings"),OpAnd(OpNEq(Var("swig"),Var("null")),Select(Var("swig"),"pythonSupport"))),Assert(OpImpl(Var("javaSwigBindings"),OpAnd(OpNEq(Var("swig"),Var("null")),Select(Var("swig"),"javaSupport"))),Assert(OpImpl(Var("javahlBindings"),OpNEq(Var("j2sdk"),Var("null"))),Call(Select(Var("stdenv"),"mkDerivation"),Attrs([Bind("builder",Path("/foo/bar"),NoPos),Bind("db4",If(Var("localServer"),Var("db4"),Var("null")),NoPos),Bind("expat",Var("expat"),NoPos),Bind("httpServer",Var("httpServer"),NoPos),Bind("httpd",If(Var("httpServer"),Var("httpd"),Var("null")),NoPos),Bind("j2sdk",If(Var("javaSwigBindings"),Select(Var("swig"),"j2sdk"),If(Var("javahlBindings"),Var("j2sdk"),Var("null"))),NoPos),Bind("javaSwigBindings",Var("javaSwigBindings"),NoPos),Bind("javahlBindings",Var("javahlBindings"),NoPos),Bind("localServer",Var("localServer"),NoPos),Bind("name",Str("subversion-1.1.1",[]),NoPos),Bind("openssl",If(Var("sslSupport"),Var("openssl"),Var("null")),NoPos),Bind("patches",If(Var("javahlBindings"),List([Path("/javahl.patch")]),List([])),NoPos),Bind("python",If(Var("pythonBindings"),Select(Var("swig"),"python"),Var("null")),NoPos),Bind("pythonBindings",Var("pythonBindings"),NoPos),Bind("src",Call(Var("fetchurl"),Attrs([Bind("md5",Str("a180c3fe91680389c210c99def54d9e0",[]),NoPos),Bind("url",Str("http://subversion.tigris.org/tarballs/subversion-1.1.1.tar.bz2",[]),NoPos)])),NoPos),Bind("sslSupport",Var("sslSupport"),NoPos),Bind("swig",If(OpOr(Var("pythonBindings"),Var("javaSwigBindings")),Var("swig"),Var("null")),NoPos)])),NoPos),NoPos),NoPos),NoPos),NoPos),NoPos),NoPos),NoPos)
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