Infer input type of lambda based on 2nd argument to map() #438

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1. yangdanny97 commented on Jun 16, 2025

   

   yangdanny97

   on Jun 16, 2025

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   This is a bit tricky, we'll need to use the type of the second argument to map's constructor as part of the contextual type for the first argument. Right now I suspect we're just evaluating arguments left to right.
2. yangdanny97

   added

   typechecking

   on Jun 16, 2025
3. yangdanny97

   added the

   Bug

   issue type on Jun 16, 2025
4. yangdanny97

   changed the title [-]map() does not infer types for lambda expressions[/-] [+]Infer input type of lambda based on 2nd argument to map()[/+] on Jun 16, 2025
5. samwgoldman commented on Jan 15, 2026

   

   samwgoldman

   on Jan 15, 2026

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   Making contextual typing work for calls like this is part of the scope of #105. Going to leave this open because it's a good example, and we could solve #105 without fixing this in theory.
6. yangdanny97

   added a parent issue on Jan 15, 2026

   • Function invocation pins type of arguments too early #105
7. rchen152

   marked this as blocked on Apr 30, 2026

   • Function invocation pins type of arguments too early #105
8. rchen152

   removed a parent issue on Apr 30, 2026

   • Function invocation pins type of arguments too early #105
9. asukaminato0721

   self-assigned this

   on Aug 19, 2026
10. meta-codesync

    added a commit that references this issue on Aug 20, 2026

    fix Infer input type of lambda based on 2nd argument to map() #438 (#…

    ...

    fdb78cf
11. meta-codesync

    closed this as completedin fdb78cfon Aug 20, 2026