iris

small scheme interpreter
git clone git://git.2f30.org/iris.git
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commit a253fe487b61b0f734d8e4d38fcbbcbe2afd7f76
parent a29d9e01a68ebf4bfa8dd66452358cb3610ee46d
Author: sin <sin@2f30.org>
Date:   Fri May 16 11:46:41 +0100

Add null predicate

Diffstat:
parser.c | 22++++++++++++++++++++++
1 file changed, 22 insertions(+), 0 deletions(-)
diff --git a/parser.c b/parser.c @@ -75,6 +75,7 @@ static struct object *evalset(struct object *); /* primitive procedures */ static struct object *evalboolean(struct object *); static struct object *evaldiff(struct object *); +static struct object *evalnull(struct object *); static struct object *evalplus(struct object *); struct { @@ -96,6 +97,7 @@ struct { } procs[] = { { .name = "boolean", .fn = evalboolean }, { .name = "diff", .fn = evaldiff }, + { .name = "null", .fn = evalnull }, { .name = "plus", .fn = evalplus }, }; @@ -465,6 +467,26 @@ evaldiff(struct object *o) } static struct object * +evalnull(struct object *o) +{ + struct object *arg; + + if (o->type != OPair) + return NULL; + if (car(o)->type != OIdentifier || + strcmp(car(o)->d.i.s, "null") != 0) + return NULL; + arg = eval(cadr(o)); + if (arg->type == OError) + return arg; + if (caddr(o)) + return error("multiple arguments"); + if (arg->type == OEmptylist) + return boolean(true); + return boolean(false); +} + +static struct object * doplus(struct object *o, struct object *n) { struct object *otmp;