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pp:l04xx [2020/03/20 21:33] pdmatei |
pp:l04xx [2020/04/07 15:11] (current) pdmatei |
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| - | ======= Programming with ADTs ======= | + | ======= 6. Programming with ADTs ======= |
| 1. A **dictionary** is a collection of key-value pairs, which we can represent in Haskell as a list of pairs ''(String,Integer)'' where ''String'' is the key type and ''Integer'' is the value type: | 1. A **dictionary** is a collection of key-value pairs, which we can represent in Haskell as a list of pairs ''(String,Integer)'' where ''String'' is the key type and ''Integer'' is the value type: | ||
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| </code> | </code> | ||
| - | 4. Implement a function which takes a dictionary of program variables, a program expression ''PExpr'', and evaluates it. For instance: ''eval_pexpr [("x",2),("y",1)] ((Var "x") :+: (Var "y"))'' returns 3. | + | 4. Implement a function which takes a dictionary of program variables, a program expression ''PExpr'', and evaluates it. For instance: ''eval_pexpr [("x",2),("y",1)] ( (Var "x") :+: (Var "y") )'' returns 3. |
| <code haskell> | <code haskell> | ||
| eval_pexpr :: Dict -> PExpr -> Integer | eval_pexpr :: Dict -> PExpr -> Integer | ||