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moremacros

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Various useful forms.

moremacros

Usage

(require-extension moremacros)

str#

(str# STRING)syntax

Allows substitution of embedded Scheme expressions prefixed with # and optionally enclosed in curly brackets. Two consecutive #s are translated to a single #.

Similar to the #<# multi-line string.

type-case

(type-case EXPRESSION [(TYPE-CASE BODY ...) ...]))syntax

Expands into a form that selects a TYPE-CASE based on the type of the EXPRESSION.

A TYPE-CASE is:

symbol
the base name of a type predicate
(symbol symbol...)
a list of base names
else
an else clause

The actual name of the predicate is built from the base name and a ? suffix. So a base name number has the predicate number?.

(use moremacros)

(type-case 23
  ((symbol string char) 'symbolic)
  (number               'numeric)
  (else                 'otheric) )
;=> numeric

type-case*

(type-case* EXPRESSION [(TYPE-TEST BODY ...) ...]))syntax

Like type-case but binds local variable it to the value of EXPRESSION.

(use moremacros)

(type-case* 23
  ((symbol string char) (list it 'symbolic) )
  (number               (list it 'numeric) )
  (else                 (list it 'otheric) ) )
;=> (23 numeric)

whennot

(whennot TEST [BODY ...]))syntax

Synonym for miscmacros#unless.

swap-set!

(swap-set! VAR1 VAR2))syntax

Swap settings of VAR1 & VAR2.

Like (exchange! VAR1 VAR2) but lower overhead.

fluid-set!

(fluid-set! VAR VAL ...))syntax

Set each variable VAR to the value VAL in parallel.

stiff-set!

(stiff-set! VAR VAL ...))syntax

Set each variable VAR to the value VAL in series.

set!/op

(set!/op VAR OP ARG...))syntax

Sets VAR to the value of (OP ARG...), where an occurrence of <> in ARG... is replaced with VAR.

When there is no occurrence of <> in ARG... the template (OP <> ARG...) is used.

Similar to the C language family <l-value> <bin-op-assign> <r-value>.

assure

(assure EXPRESSION [ERROR-ARGUMENT...]))syntax

When EXPRESSION yields value #f invoke (error ERROR-ARGUMENT...), otherwise return value.

make-reference-let

(make-reference-let NAME REFERENCE-FUNCTION)syntax

NAME is a symbol, the name of the generated reference-let macro.

REFERENCE-FUNCTION is a (procedure (* * *) *) with arguments:

The REFERENCE-FUNCTION is to return the value for KEY in the TABLE, otherwise the DEFAULT value.

The generated macro has the signature:

(NAME TABLE (VAR | (VAR) | (VAR KEY [DEFAULT]) ...) BODY ...)syntax
TABLE
some data-structure instance that reifies a set of key+value abstraction
KEY
identifier for a possible entry in the TABLE
DEFAULT
in case an entry for the KEY does not exist

Decompose TABLE entries into variable bindings. Should the KEY not be a symbol, or the desired variable name VAR, as 'VAR, is not the key, the (VAR KEY [DEFAULT]) form can be used.

The default for DEFAULT is #f.

The BODY... is evaluated with the specified bindings.

See hash-let for an example of use.

warning-guard

(warning-guard GETTER-NAME TYPENAME [BODY...])syntax

Constructs a variable or parameter guard procedure that generates a warning and returns the current value when the type predicate fails, otherwise the submitted value is returned.

TYPENAME is an identifier and TYPENAME? is a (procedure (*) boolean).

GETTER-NAME is an identifier and the name of a procedure _ *.

BODY is zero or more expressions that are performed after a successful typecheck. Note that since the guard is invoked by a variable or parameter during initialization, so will be the body code.

(use variable-item)

(warning-guard some-var integer)

checked-guard

(checked-guard GETTER-NAME TYPENAME [BODY...])syntax

Constructs a variable or parameter guard procedure that uses a type check procedure to verify the submitted value is returned.

TYPENAME is an identifier and check-TYPENAME is a (procedure ((or #f symbol) * #!optional (or symbol string)) *). See check-errors for a suite of these procedures.

GETTER-NAME is an identifier and the name of a procedure _ *.

BODY is zero or more expressions that are performed after a successful typecheck. Note that since the guard is invoked by a variable or parameter during initialization, so will be the body code.

(use variable-item type-checks)

(checked-guard some-var integer)

define-warning-parameter

(define-warning-parameter NAME INIT TYPENAME [BODY...])syntax

Wrapper around define-parameter and warning-guard that defines the parameter NAME to the parameter.

NAME is an identifier.

INIT is some Scheme object.

TYPENAME is an identifier. The basename of a type predicate; see warning-guard.

BODY... as for warning-guard.

(use parameter-item)

(define-warning-variable scale * procedure)
(scale 23) ;=> Warning: (foo) "bad argument type - not a procedure" 23

define-checked-parameter

(define-checked-parameter NAME INIT TYPENAME [BODY...])syntax

Wrapper around define-parameter and checked-guard that defines the variable NAME to the parameter.

NAME is an identifier.

INIT is some Scheme object.

TYPENAME is an identifier. The basename of a type predicate; see checked-guard.

BODY... as for checked-guard.

(use parameter-item)

(define-checked-parameter scale * procedure)
(scale 23) ;=> Error: (foo) "bad argument type - not a procedure" 23

hash-let

Usage

(require-extension hash-let)

hash-let

(hash-let HASH-TABLE (VAR | (VAR) | (VAR KEY [DEFAULT]) ...) BODY ...)syntax

Decompose HASH-TABLE entries into variable bindings. Should the KEY not be a symbol, or the desired variable name VAR is not the key, the (VAR KEY [DEFAULT]) form can be used.

The default value for a missing hash-table entry is #f but can be specified with the (VAR KEY DEFAULT) form.

The BODY... is evaluated with the specified bindings.

(use hash-let srfi-69)

(define tbl (make-hash-table))

(hash-table-set! tbl 'abc "commercial network")
(hash-table-set! tbl "abc" "commercial network")
(hash-table-set! tbl 'cbs "commercial network")
(hash-table-set! tbl "cbs" "commercial network")

(hash-let tbl ((abc)
               (cbs "cbs")
               (pbs (string-append "p" "bs") #t)
               tbs)
  (print 'abc " is a " abc) (print "cbs" " is a " cbs)
  (print (string-append "p" "bs") " is a " pbs)
  (print 'tbs " is a " tbs) )

This prints the following:

abc is a commercial network
cbs is a commercial network
pbs is a #t
tbs is a #f

Numeric Macros

Usage

(require-extension numeric-macros)

++

(++ VAL)syntax

Read-only increment.

When VAL is a numeric literal the strongest operation available is used in the generated expression, based on the type of the literal.

--

(-- VAL)syntax

Read-only decrement.

When VAL is a numeric literal the strongest operation available is used in the generated expression, based on the type of the literal.

fx++

(fx++ VAL)syntax

Read-only fixnum increment.

fx--

(fx-- VAL)syntax

Read-only fixnum decrement.

fp++

(fp++ VAL)syntax

Read-only flonum increment.

fp--

(fp-- VAL)syntax

Read-only flonum decrement.

fl++

(fl++ VAL)syntax

Read-only flonum increment.

R6RS nomenclature.

fl--

(fl-- VAL)syntax

Read-only flonum decrement.

R6RS nomenclature.

++!

(++! VAR)syntax

Mutable increment.

--!

(--! VAR)syntax

Mutable decrement.

fx++!

(fx++! VAR)syntax

Mutable fixnum increment.

fx--!

(fx--! VAR)syntax

Mutable fixnum decrement.

fp++!

(fp++! VAR)syntax

Mutable flonum increment.

fp--!

(fp--! VAR)syntax

Mutable flonum decrement.

fl++!

(fl++! VAR)syntax

Mutable flonum increment.

R6RS nomenclature.

fl--!

(fl--! VAR)syntax

Mutable flonum decrement.

R6RS nomenclature.

Requirements

check-errors

Author

Kon Lovett

Version history

1.4.0
Added warning-guard, checked-guard, define-warning-parameter, & define-checked-parameter.
1.3.0
Added make-reference-let and hash-let, w/ new syntax.
1.2.2
Added set#. Removed make-reference-let and hash-let.
1.2.1
Moved variable-item to own extension.
1.2.0
Aligned make-variable better with make-parameter.
1.1.1
1.1.0
Added make-reference-let. Split make-variable & define-variable into own module variable-item.
1.0.0
Hello

License

Copyright (C) 2010-2017 Kon Lovett. All rights reserved.

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the Software), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED ASIS, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

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