Re: FLI type error

  I get "Hello".

On 3/7/2026 2:11 PM, David McClain wrote:
> (coerce "Hello" 'base-string)
>
> But, is LW smart enough to see the transitive closure from GLCHAR to BASE-CHAR?
>
>> On Mar 7, 2026, at 12:08, Paul Werkowski (as pw at snoopy dot qozzy dot com) <[email protected]> wrote:
>>
>> No, *default-character-element-type* is BASE-CHAR.
>>
>> On 3/7/2026 2:04 PM, David McClain wrote:
>>> Web search shows GLCHAR is 8-bit char (ASCII ?). We had 30+ years of stability and simplicity once EBCDIC gave way to ASCII.
>>>
>>> But my recent experience with the Rust world shows that simplicity is no longer relevant. Very possibly you are using Wide Lisp chars instead of BASE-CHAR?
>>>
>>>
>>>
>>>> On Mar 7, 2026, at 11:24, Paul Werkowski (as pw at snoopy dot qozzy dot com) <[email protected]> wrote:
>>>>
>>>> Well, GLCHAR is lisp :char. I see that the FLI manual has things like convert-to-foreign-type etc. I shall poke around in there for awhile.
>>>>
>>>> Thanks for the suggestion,
>>>> PW
>>>>
>>>> On 3/7/2026 12:43 PM, David McClain wrote:
>>>>> No… I  now see.
>>>>>
>>>>> It appears that Lisp cannot automatically convert your Lisp string to the required C type (:POINTER OPENGL:GLCHAR). There has always been a sometimes conversion ability to allow Lisp strings to become C strings. But your required type is not a “C String” kind of pointer.
>>>>>
>>>>> Yes, even though it probably really is a C string type, I have no idea whether OPENGL:GLCHAR is a 8-bit ASCII char, or a Unicode wide char, etc. So probably no implicit LW conversions would apply.
>>>>>
>>>>> IOW… you probably now have to provide your own explicit conversions.
>>>>>
>>>>> - DM
>>>>>
>>>>>> On Mar 7, 2026, at 10:37, David McClain <[email protected]> wrote:
>>>>>>
>>>>>>> Both of these get a runtime error
>>>>>>> "aPos"  (and "triangleColor") cannot be converted to foreign type
>>>>>>> (:POINTER   OPENGL:GLCHAR).
>>>>>>>
>>>>>> Offhand… did the OpenGL API change since 10 years ago? Perhaps now expects an array of char, or a string pointer?
>>>>>>
>>>>>>
>>>>>>
>>>>>>> On Mar 7, 2026, at 09:59, Paul Werkowski (as pw at snoopy dot qozzy dot com) <[email protected]> wrote:
>>>>>>>
>>>>>>> I'm looking at some code from 5-10 years ago, experimenting with OPENGL, that uses the LW example code to setup the interface. The icosahedron example works fine so no issue there.
>>>>>>>
>>>>>>> Here are two fragments from my code.
>>>>>>>
>>>>>>> (let ((pos-attr (gl-get-attrib-location shader-pgm "aPos"))
>>>>>>>
>>>>>>> (let((unicolor (gl-get-uniform-location
>>>>>>>                             shader-pgm "triangleColor")))
>>>>>>>
>>>>>>> Both of these get a runtime error
>>>>>>> "aPos"  (and "triangleColor") cannot be converted to foreign type
>>>>>>> (:POINTER   OPENGL:GLCHAR).
>>>>>>>
>>>>>>> GLCHAR is defined in opengl/types.lisp as
>>>>>>>
>>>>>>> (fli:define-c-typedef (glchar (:foreign-name "GLchar"))
>>>>>>>   :char)
>>>>>>>
>>>>>>> Same issue with both LWW 8.1.2 64 bit and 7.1.2 32 bit.
>>>>>>>
>>>>>>> This all used to work. What could be wrong???
>>>>>>>
>>>>>>> Puzzled again,
>>>>>>> Paul
>>>>>>>
>>>>>>>
>>>>>>>
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