► |  | Ht DP: Languages as Libraries

1 | Ht DP Beginning Student
2 | Ht DP Beginning Student with Abbreviations
3 | Ht DP Intermediate Student
4 | Ht DP Intermediate Student with Lambda
5 | Ht DP Advanced Student
6 | Pretty Big Text (Legacy Language)
7 | Pretty Big (Legacy Language)
8 | posns in Ht DP Languages
9 | Image Equality in Ht DP Languages
10 | Primitives in Ht DP Beginner

1`` Ht DP Beginning Student
2`` Ht DP Beginning Student with Abbreviations
3`` Ht DP Intermediate Student
4`` Ht DP Intermediate Student with Lambda
5`` Ht DP Advanced Student
6`` Pretty Big Text (Legacy Language)
7`` Pretty Big (Legacy Language)
8`` posns in Ht DP Languages
posn
9`` Image Equality in Ht DP Languages
image=?
10`` Primitives in Ht DP Beginner
define-primitive
provide-primitive
provide-primitives
define-higher-order-primitive
provide-higher-order-primitive
first-order->higher-order

Version: 4.2.4
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## HtDP: Languages as Libraries

### 1`` HtDP Beginning Student

(require lang/htdp-beginner)

The lang/htdp-beginner module provides the Beginning Student language for How to Design Programs; see Beginning Student.

### 2`` HtDP Beginning Student with Abbreviations

(require lang/htdp-beginner-abbr)

The lang/htdp-beginner-abbr module provides the Beginning Student with Abbreviations language for How to Design Programs; see Beginning Student with List Abbreviations.

### 3`` HtDP Intermediate Student

(require lang/htdp-intermediate)

The lang/htdp-intermediate module provides the Intermediate Student language for How to Design Programs; see Intermediate Student.

### 4`` HtDP Intermediate Student with Lambda

(require lang/htdp-intermediate-lambda)

The lang/htdp-intermediate-lambda module provides the Intermediate Student with Lambda language for How to Design Programs; see Intermediate Student with Lambda.

### 5`` HtDP Advanced Student

(require lang/htdp-advanced)

The lang/htdp-advanced module provides the Advanced Student language for How to Design Programs; see Advanced Student.

### 6`` Pretty Big Text (Legacy Language)

(require lang/plt-pretty-big-text)

The lang/plt-pretty-big-text module is similar to the HtDP Advanced Student language, but with more of PLT Scheme’s libraries. It provides the bindings of mzscheme, mzlib/etc, mzlib/file, mzlib/list, mzlib/class, mzlib/unit, mzlib/include, mzlib/defmacro, mzlib/pretty, mzlib/string, mzlib/thread, mzlib/math, mzlib/match, mzlib/shared, and lang/posn.

### 7`` Pretty Big (Legacy Language)

(require lang/plt-pretty-big)

The lang/plt-pretty-big module extends lang/plt-pretty-big-text with scheme/gui/base and lang/imageeq. This language corresponds to the Pretty Big Scheme legacy language in DrScheme.

### 8`` posns in HtDP Languages

(require lang/posn)

(struct posn (x y))
x : any/c
y : any/c

The posn structure type that is also provided by lang/htdp-beginner.

### 9`` Image Equality in HtDP Languages

(require lang/imageeq)

(image=? i1 i2) → boolean?
i1 : (is-a?/c image-snip%)
i2 : (is-a?/c image-snip%)

The image-comparison operator that is also provided by lang/htdp-beginner.

### 10`` Primitives in HtDP Beginner

(require lang/prim)

The lang/prim module several syntactic forms for use by the implementors of teachpacks, when the teachpack is to be used with the How to Design Programs Beginner Student languages. In Beginner Student, primitive names (for built-in procedures) are distinguished from other types of expressions, so that they can be syntactically restricted to application positions.

(define-primitive id proc-id)

Defines id to be a primitive operator whose implementation is proc-id, and that takes no procedures as arguments. Normally, id is exported from the teachpack and proc-id is not.

(provide-primitive id)

Like define-primitive, but the existing function id is exported as the primitive operator named id. An alternative to define-primitive.

(provide-primitives id ...)

Multiple-identifier version of provide-primitive.

(define-higher-order-primitive id proc-id (arg ...))

Defines id to be a primitive operator whose implementation is proc-id. Normally, id is exported from the teachpack and proc-id is not.

For each non-procedure argument, the corresponding arg should be an underscore. For each procedure argument, the corresponding arg should be the usual name of the procedure.

Examples:
(define-higher-order-primitive convert-gui convert-gui/proc (f2c))

(provide-higher-order-primitive id (arg ...))

Like define-higher-order-primitive, but the existing function id is exported as the primitive operator named id. An alternative to define-higher-order-primitive.

(first-order->higher-order expr)

If expr is an identifier for a first-order function (either a primitive or a function defined within Beginner Student), produces the function as a value; otherwise, the form is equivalent to expr.

This form is mainly useful for implementing syntactic forms that, like the application of a higher-order primitive, allow first-order bindings to be used in an expression position.

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