Module 04/05 Flashcards

Front 1

Immutable

Back 1

Cannot be modified after it is created.

Front 2

Function Binding

Back 2

Syntax:

fun x0 (x1 : t1, ... , xn : tn) = e

Type-checking:

- adds binding x0 : (t1 * ... * tn) -> t if:

- can type-check body e to have t in the static environment containing:

• "enclosing" static environment (earlier bindings)

• x1 : t1, ... , xn : tn (arguments with their types)

• x0 : (t1 * ... * tn) -> t (for recursion)

Evaluation:

A function is a value.

- adds x0 to environment so later expressions can call it

- function-call semantics will also allow recursion

Front 3

Recursive

Back 3

Repeating itself using a more simplified version until a base argument is reached

Front 4

Type interface

Back 4

Automatic deduction of the data type of an expression

Front 5

Function Calls

Back 5

Syntax:

e0 (e1, ..., en) with the parentheses optional if there is exactly one argument

Type-checking:

e0 has a type that looks like t1 * ... * tn -> t and for 1 ≤ i ≤ n,ei has type ti. Then the whole call has type t

Evaluation:

use the environment at the point of the call to evaluate e0 to v0, e1 to v1, ..., en to vn. Then v0 must be a function (it will be assuming the call type-checked) and we evaluate the function’s body in an environment extended such that the function arguments map to v1, ..., vn