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* @-patterns as in Haskell. For instance, in a function definition

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f = args @ {x, y, z}: ...;

  `args' refers to the argument as a whole, which is further
  pattern-matched against the attribute set pattern {x, y, z}.
This commit is contained in:
Eelco Dolstra 2008-08-14 12:53:29 +00:00
parent e818838412
commit 1b962fc720
10 changed files with 106 additions and 46 deletions
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13
src/libexpr/parser.y
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@ -211,7 +211,8 @@ static void freeAndUnprotect(void * p)
}
%type <t> start expr expr_function expr_if expr_op
%type <t> expr_app expr_select expr_simple bind inheritsrc formal pattern
%type <t> expr_app expr_select expr_simple bind inheritsrc formal
%type <t> pattern pattern2
%type <ts> binds ids expr_list formals string_parts ind_string_parts
%token <t> ID INT STR IND_STR PATH URI
%token IF THEN ELSE ASSERT WITH LET IN REC INHERIT EQ NEQ AND OR IMPL
@ -319,6 +320,11 @@ ind_string_parts
;
pattern
: pattern2 '@' pattern { $$ = makeAtPat($1, $3); }
| pattern2
;
pattern2
: ID { $$ = makeVarPat($1); }
| '{' formals '}' { $$ = makeAttrsPat($2); }
;
@ -394,6 +400,7 @@ static void checkPatternVars(ATerm pos, ATermMap & map, Pattern pat)
{
ATerm name;
ATermList formals;
Pattern pat1, pat2;
if (matchVarPat(pat, name)) {
if (map.get(name))
throw EvalError(format("duplicate formal function argument `%1%' at %2%")
@ -410,6 +417,10 @@ static void checkPatternVars(ATerm pos, ATermMap & map, Pattern pat)
map.set(name, name);
}
}
else if (matchAtPat(pat, pat1, pat2)) {
checkPatternVars(pos, map, pat1);
checkPatternVars(pos, map, pat2);
}
else abort();
}