Add if primitive procedure

4 files changed, 75 insertions, 33 deletions

diff --git a/examples/booleans.bdl b/examples/booleans.bdl
index d248bf8..d526f25 100644
--- a/examples/booleans.bdl
+++ b/examples/booleans.bdl
@@ -3,43 +3,54 @@
 ;;
 
 ;; Boolean test.
-(print "(boolean? true) -> ")   (boolean? true)
-(print "(boolean? false) -> ")   (boolean? false)
-(print "(boolean? 1) -> ")   (boolean? 1)
-(print "(boolean? 5) -> ")   (boolean? 5)
+(print "(boolean? true) -> ")       (boolean? true)
+(print "(boolean? false) -> ")      (boolean? false)
+(print "(boolean? 1) -> ")          (boolean? 1)
+(print "(boolean? 5) -> ")          (boolean? 5)
 (print "(boolean? \"string\") -> ") (boolean? "string")
-(print "(boolean? (+ 1 2 3)) -> ")   (boolean? (+ 1 2 3))
-(print "(boolean? (not 1)) -> ")   (boolean? (not 1))
+(print "(boolean? (+ 1 2 3)) -> ")  (boolean? (+ 1 2 3))
+(print "(boolean? (not 1)) -> ")    (boolean? (not 1))
 
 ;; Not.
-(print "(not true) -> ")   (not true)
-(print "(not false) -> ")   (not false)
-(print "(not (not true)) -> ")   (not (not true))
-(print "(not (not false)) -> ")   (not (not false))
-(print "(not 1) -> ")   (not 1)
-(print "(not (not 1)) -> ")   (not (not 1))
-(print "(not \"string\") -> ") (not "string")
+(print "(not true) -> ")             (not true)
+(print "(not false) -> ")            (not false)
+(print "(not (not true)) -> ")       (not (not true))
+(print "(not (not false)) -> ")      (not (not false))
+(print "(not 1) -> ")                (not 1)
+(print "(not (not 1)) -> ")          (not (not 1))
+(print "(not \"string\") -> ")       (not "string")
 (print "(not (not \"string\")) -> ") (not (not "string"))
 
 ;; And.
-(print "(and 1 \"string\" 4 true) -> ") (and 1 "string" 4 true)
-(print "(and true true true) -> ")   (and true true true)
-(print "(and (+ 1 2 3)) -> ")   (and (+ 1 2 3))
-(print "(and false false false) -> ")   (and false false false)
-(print "(and true false false) -> ")   (and true false false)
-(print "(and false true false) -> ")   (and false true false)
-(print "(and false true true) -> ")   (and false true true)
-(print "(and (not false) true true) -> ")   (and (not false) true true)
+(print "(and 1 \"string\" 4 true) -> ")   (and 1 "string" 4 true)
+(print "(and true true true) -> ")        (and true true true)
+(print "(and (+ 1 2 3)) -> ")             (and (+ 1 2 3))
+(print "(and false false false) -> ")     (and false false false)
+(print "(and true false false) -> ")      (and true false false)
+(print "(and false true false) -> ")      (and false true false)
+(print "(and false true true) -> ")       (and false true true)
+(print "(and (not false) true true) -> ") (and (not false) true true)
 
 ;; Or.
-(print "(or 1 \"string\" 4 true) -> ") (or 1 "string" 4 true)
-(print "(or false 1) -> ")   (or false 1)
-(print "(or false \"string\") -> ") (or false "string")
-(print "(or false) -> ")   (or false)
-(print "(or true true true) -> ")   (or true true true)
-(print "(or false false false) -> ")   (or false false false)
-(print "(or true false false) -> ")   (or true false false)
-(print "(or false true false) -> ")   (or false true false)
-(print "(or false true true) -> ")   (or false true true)
-(print "(or (not false) true true) -> ")   (or (not false) true true)
-(print "(or (not true) false) -> ")   (or (not true) false)
+(print "(or 1 \"string\" 4 true) -> ")   (or 1 "string" 4 true)
+(print "(or false 1) -> ")               (or false 1)
+(print "(or false \"string\") -> ")      (or false "string")
+(print "(or false) -> ")                 (or false)
+(print "(or true true true) -> ")        (or true true true)
+(print "(or false false false) -> ")     (or false false false)
+(print "(or true false false) -> ")      (or true false false)
+(print "(or false true false) -> ")      (or false true false)
+(print "(or false true true) -> ")       (or false true true)
+(print "(or (not false) true true) -> ") (or (not false) true true)
+(print "(or (not true) false) -> ")      (or (not true) false)
+
+;; If.
+(print "(if true true false) -> ")                          (if true true false)
+(print "(if false true false) -> ")                         (if false true false)
+(print "(if true (+ 1 2 3) 0) -> ")                         (if true (+ 1 2 3) 0)
+(print "(if false (+ 1 2 3) 0) -> ")                        (if false (+ 1 2 3) 0)
+(print "(if (or true false) (+ 1 2 3) (+ 7 8 9)) -> ")      (if (or true false) (+ 1 2 3) (+ 7 8 9))
+(print "(if (or false false) (+ 1 2 3) (+ 7 8 9)) -> ")     (if (or false false) (+ 1 2 3) (+ 7 8 9))
+(print "(if (or (+ 1 2 3) false) (+ 1 2 3) (+ 7 8 9)) -> ") (if (or (+ 1 2 3) false) (+ 1 2 3) (+ 7 8 9))
+(print "(if true 7) -> ")                                   (if true 7)
+(print "(if false 7) -> ")                                  (if false 7)
diff --git a/src/bootstrap/main.c b/src/bootstrap/main.c
index a8ba7bc..8ec1231 100755
--- a/src/bootstrap/main.c
+++ b/src/bootstrap/main.c
@@ -40,6 +40,7 @@ init(void) {
     environment[env_n++] = (EnvSymbol){MAKE_SYM("not"), make_procedure(proc_not)};
     environment[env_n++] = (EnvSymbol){MAKE_SYM("and"), make_procedure(proc_and)};
     environment[env_n++] = (EnvSymbol){MAKE_SYM("or"), make_procedure(proc_or)};
+    environment[env_n++] = (EnvSymbol){MAKE_SYM("if"), make_procedure(proc_if)};
     environment[env_n++] = (EnvSymbol){MAKE_SYM("display"), make_procedure(proc_display)};
     environment[env_n++] = (EnvSymbol){MAKE_SYM("print"), make_procedure(proc_print)};
 }
diff --git a/src/bootstrap/primitives.c b/src/bootstrap/primitives.c
index 97058f9..61ce360 100644
--- a/src/bootstrap/primitives.c
+++ b/src/bootstrap/primitives.c
@@ -309,5 +309,26 @@ proc_or(Object *args) {
     return obj_false;
 }
 
-// TODO: if/cond
+Object *
+proc_if(Object *args) {
+    if (args->type != OBJ_TYPE_PAIR || args->cdr->type != OBJ_TYPE_PAIR) {
+        fprintf(stderr, "error: wrong number of arguments.\n");
+        return NULL;
+    }
+
+    Object *condition = eval(args->car);
+    if (condition == obj_true) {
+        Object *ret = eval(args->cdr->car);
+        return ret;
+    }
+    if (args->cdr->cdr != obj_nil) {
+        Object *ret = eval(args->cdr->cdr->car);
+        return ret;
+    }
+
+    return obj_nil;
+}
+
+// TODO: cond
+// TODO: equality greater than smaller than...
 // TODO: fixnum left/right shift, mask, invert
diff --git a/tests/booleans_expected.txt b/tests/booleans_expected.txt
index 81f0313..d05d314 100644
--- a/tests/booleans_expected.txt
+++ b/tests/booleans_expected.txt
@@ -32,3 +32,12 @@
 (or false true true) -> true
 (or (not false) true true) -> true
 (or (not true) false) -> false
+(if true true false) -> true
+(if false true false) -> false
+(if true (+ 1 2 3) 0) -> 6
+(if false (+ 1 2 3) 0) -> 0
+(if (or true false) (+ 1 2 3) (+ 7 8 9)) -> 6
+(if (or false false) (+ 1 2 3) (+ 7 8 9)) -> 24
+(if (or (+ 1 2 3) false) (+ 1 2 3) (+ 7 8 9)) -> 6
+(if true 7) -> 7
+(if false 7) -> ()