Compilers & Runtimes.

How source text becomes something that runs: the front end that reads it, the passes that rewrite it, and the runtime that executes it and reclaims its memory. Covers 10 topics.

• Compilers & Runtimes · 1 of 3

  Lexical Analysis

  How many NAME and OP tokens does Python's tokenize.generate_tokens produce for a<=b?

  AFour: a, <, =, bBThree: a, <=, bCOne token: a<=bDTwo: a<= and b

• Compilers & Runtimes · 2 of 3

  Parsing & ASTs

  Why is a function call an interior AST node rather than a leaf?

  AIt is always the root of the treeBIt has callee and argument childrenCIt holds the raw source text inlineDIt must store a runtime return value

• Compilers & Runtimes · 3 of 3

  Semantic Analysis & Types

  Why does moving a type check from run time to compile time cost the language something?

  AThe checker must prove the property from the code alone, so it rejects some programs that would run fineBThe checker must give up type inference, so every expression in the program needs an explicit annotationCThe checker must see every runtime value, so compilation has to execute the program before it can finishDThe compiled program must repeat the check at run time, so each call pays for the same check a second time