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| author | dos-reis <gdr@axiomatics.org> | 2007-12-12 05:18:09 +0000 |
|---|---|---|
| committer | dos-reis <gdr@axiomatics.org> | 2007-12-12 05:18:09 +0000 |
| commit | 59c74f79255a713a633fc6b7ca3e18ff89d018b7 (patch) | |
| tree | 5c5efd8048fe58399dcd84d9d0f19f130e5e949e /src/algebra/syntax.spad | |
| parent | 0d6564c18ff92a96f98c235b82a0da82556e5098 (diff) | |
| download | open-axiom-59c74f79255a713a633fc6b7ca3e18ff89d018b7.tar.gz | |
* syntax.spad (nil?$Syntax): New predicate.
Diffstat (limited to 'src/algebra/syntax.spad')
| -rw-r--r-- | src/algebra/syntax.spad | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/src/algebra/syntax.spad b/src/algebra/syntax.spad index 80bee21e..df62adb5 100644 --- a/src/algebra/syntax.spad +++ b/src/algebra/syntax.spad @@ -83,6 +83,9 @@ Syntax(): Public == Private where buildSyntax: (%, List %) -> % ++ buildSyntax(op, [a1, ..., an]) builds a syntax object for op(a1,...,an). + nil?: % -> Boolean + ++ nil?(s) is true when `s' is a syntax for the constant nil. + getOperator: % -> Union(Integer, DoubleFloat, Symbol, String, %) ++ getOperator(x) returns the operator, or tag, of the syntax `x'. ++ The return value is itself a syntax if `x' really is an @@ -147,6 +150,9 @@ Syntax(): Public == Private where buildSyntax(op: %, l: List %): % == cons(op, l) pretend % + nil? x == + null? rep x + getOperator x == atom? rep x => userError "atom as operand to getOperator" s := car rep x |