diff options
Diffstat (limited to 'src/interp/compiler.boot')
| -rw-r--r-- | src/interp/compiler.boot | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/src/interp/compiler.boot b/src/interp/compiler.boot index 3245b887..81860046 100644 --- a/src/interp/compiler.boot +++ b/src/interp/compiler.boot @@ -1405,7 +1405,10 @@ compColonInside(x,m,e,m') == compIs: (%Form,%Mode,%Env) -> %Maybe %Triple compIs(["is",a,b],m,e) == - [aval,am,e] := comp(a,$EmptyMode,e) or return nil + [aval,am,e] := comp(a,$EmptyMode,e) or + stackAndThrow('"Cannot determine the type of the expression %1b",[a]) + not isCategoryForm(am,e) => + stackAndThrow('"Expression %1b does not designate a domain",[a]) [bval,bm,e] := comp(b,$EmptyMode,e) or return nil T:= [["domainEqual",aval,bval],$Boolean,e] coerce(T,m) |