Best programming language and bytecode specifications. (By their rigidness)
- SML (just go read it, it is mathematical article)
- Webassembly (for example: https://webassembly.github.io/spec/core/valid/instructions.html#xref-syntax-instructions-syntax-instr-control-mathsf-if-xref-syntax-instructions-syntax-blocktype-mathit-blocktype-xref-syntax-instructions-syntax-instr-mathit-instr-1-ast-xref-syntax-instructions-syntax-instr-control-mathsf-else-xref-syntax-instructions-syntax-instr-mathit-instr-2-ast-xref-syntax-instructions-syntax-instr-control-mathsf-end )
- Ecmascript (see my summary: https://github.com/rust-lang/rfcs/pull/3355#issuecomment-1385713351 )