cs330_f2016:lab16
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cs330_f2016:lab16 [2016/11/26 17:53] morse |
cs330_f2016:lab16 [2021/06/30 23:42] (current) |
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| - | ** This is a draft version of the assignment. Do not start on it until this line is removed. ** | ||
| ====Objective:==== | ====Objective:==== | ||
| Line 8: | Line 7: | ||
| ====Deliverable:==== | ====Deliverable:==== | ||
| - | Implement the CITypes interpreter using the provided shell. | + | Implement the CITypes interpreter using [[http://liftothers.org/dokuwiki/doku.php?id=cs330_f2016:lab16shell|the provided shell]]. |
| === Language Overview === | === Language Overview === | ||
| - | The CITypes language is based on the CI5 language, just like your Extended Interpreter. | + | The CITypes language is based on the CI3 language, just like your Extended Interpreter. |
| ** You do not need to add any functionality from your previous assignments. ** | ** You do not need to add any functionality from your previous assignments. ** | ||
| To make the type system more interesting, the CITypes language adds booleans and numeric lists. | To make the type system more interesting, the CITypes language adds booleans and numeric lists. | ||
| - | The "if0" function is replaced by "ifb", which requires that the conditional return a boolean value (like in Java). | ||
| A new operator "iszero" is added, which tests to see if a number is zero and returns a boolean result. | A new operator "iszero" is added, which tests to see if a number is zero and returns a boolean result. | ||
| Line 23: | Line 21: | ||
| * false | * false | ||
| - | The language also requires that the types of formal parameters be specified with the function is declared: <code>(lambda <id> : <type> <expr>)</code>. | + | The "if0" function is replaced by "ifb", which requires that the conditional return a boolean value (like in Java). |
| - | For example, a simple numeric increment function would be written as <code>(lambda x : number (+ x 1)</code>. | + | So that the language can be statically type checked, both branches of "ifb" must return the same type. |
| + | |||
| + | The language also requires that the types of formal parameters be specified with the function is declared: | ||
| + | <code lisp> | ||
| + | (lambda <id> : <type> <expr>) | ||
| + | </code> | ||
| + | To support this, the language's grammar also includes a new nonterminal "<type>", which can be "number", "boolean", "nlist", or a function type signature of the form "(<type> : <type>)". | ||
| + | |||
| + | For example, a simple numeric increment function would be written as | ||
| + | <code lisp> | ||
| + | (lambda x : number (+ x 1)) | ||
| + | </code> | ||
| + | and a function lambda that takes as input a function f from numbers to numbers would look like this: | ||
| + | <code lisp> | ||
| + | (lambda f : (number : number) (f 3)) | ||
| + | </code> | ||
| There are five new types of expressions for handling numeric lists: | There are five new types of expressions for handling numeric lists: | ||
| Line 36: | Line 49: | ||
| Here is the grammar for the CITypes language: | Here is the grammar for the CITypes language: | ||
| - | <code> | + | <code bnf> |
| <expr> ::= <number> | <expr> ::= <number> | ||
| | true | | true | ||
| Line 50: | Line 63: | ||
| | nempty | | nempty | ||
| | (ncons <expr> <expr>) | | (ncons <expr> <expr>) | ||
| - | | (nempty <expr>) | + | | (nisempty <expr>) |
| | (nfirst <expr>) | | (nfirst <expr>) | ||
| | (nrest <expr>) | | (nrest <expr>) | ||
| Line 81: | Line 94: | ||
| ** The type checker should perform no evaluation of the code, only type checking. ** | ** The type checker should perform no evaluation of the code, only type checking. ** | ||
| - | Some of the tests will involve comparing two types, and a "same_types" function is provided to do a recursive comparison. | + | In class, we went over [[lab16judgments | the type judgments for the expressions other than those that work with lists]]. |
| + | You will need to determine them for the five list-handling expressions yourself. | ||
| + | Some of the tests will involve comparing two types, and a "same_types" function is provided to do a (recursive if necessary) comparison. | ||
| - | + | When your type checker catches an error, it should throw an exception with a descriptive error message. | |
| + | ---- | ||
| ====Hints:==== | ====Hints:==== | ||
| + | |||
| + | * The "calcf" function in the CI3 interpreter that read in a test file, ran it through lex / parse / calc has been replaced with a "typef" function that similarly reads in a test file and runs it through lex / parse / type_of_expression. You can use it to run your own test cases. | ||
| + | * Make sure you test not only for validly typed expressions but for each kind of type error. | ||
cs330_f2016/lab16.1480182810.txt.gz · Last modified: 2021/06/30 23:40 (external edit)
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