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- Dictionaryscheme/skiːm/
noun
- 1. a large-scale systematic plan or arrangement for attaining a particular object or putting a particular idea into effect: British "the occupational sick pay scheme" Similar
- 2. an estate of social housing: informal Scottish "the whole scheme is plunged into darkness, bar the light in Victor's house"
verb
- 1. make plans, especially in a devious way or with intent to do something illegal or wrong: "envious of their wealth, he schemed to bring about their downfall"
- 2. arrange according to a colour scheme: "she was busy arranging flowers, scheming the candles and napkins"
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Apr 11, 2013 · As it happens, the requirement of naming procedures is so very common and provides so much power of expression, that Scheme provides a cleaner-looking shortcut to do it. Like @oscar-lopez says, define is the "special form" Scheme provides, to name things. And as far as Scheme's Interpreter is concerned, both the following definitions are identical:
Apr 20, 2011 · In Scheme it's generally good practice to avoid set! when you don't need to (and in this case you definitely don't need to). Further iterating over a list using indices is usually a bad idea as scheme's lists are linked lists and as such random access O(n) (making the last function as you want to implement it O(n^2) ).
Mar 25, 2011 · Different Scheme systems have dramatically different meanings for 'define'. In fact, Racket has recently changed the meaning of 'define' by adding new contexts in which it can occur. On the other hand, people like 'define'; it has less indentation, and it usually has a "do-what-I-mean" level of scoping allowing natural definitions of recursive and mutually recursive procedures.
Feb 19, 2014 · The reason you have a nested let here is because ytimesz can't be accessed in the same let as it is made. We have another special form for that let*. (define (test x y z) (let* ((ytimesz (* y z)) (sum (+ x ytimesz))) (dosomething sum))) letrec and letrec* are similar but allows for recursion so in a lambda you can call one of the other bound ...
May 31, 2010 · Furthermore, in Scheme all control and environment structures can be represented by lambda expressions and applications of lambdas. So, lambda is strictly more powerful than let and forms the basis of many of the interesting constructs found in Scheme. Concerning define and lambda, a top-level define adds a binding to the top-level environment.
Jan 3, 2014 · the standard and correct way to rewrite nested define s (which are recursive) is with letrec: (define foo (letrec ((bar (lambda(n) (+ n n)))) (bar 1))). which is equivalent to the (more popular) "named let " construct, (define foo (let bar ((n 1)) (+ n n))) (even though bar isn't called recursively here at all). – Will Ness.
Jan 15, 2013 · As an aside, Scheme gives you a short-hand for defining functions, which can hide the true nature of lambda. I could also define f with: (define (f x y) (+ x y)) But I wanted to make the correspondence clear. Lambdas are useful for the same reason numeric literals are useful. In Scheme, you can have functions that take other functions as arguments.
May 24, 2012 · 0. In the (rather extensive) documentation of Gambit Scheme there is no mention of a define* special form; it might be some procedure, definition, macro or special form found only in the piece of code where you saw it. You should post a link referencing the source of the code where define* is being used. edited May 25, 2012 at 1:05.
Nov 27, 2015 · Some implementations of Scheme -- like Guile (tested with version 1.8) and MIT Scheme -- provide the following shorthand notation: (define ((foo x) y) (+ x y)) (foo 5) ; => procedure ((foo 5) 3) ; => 8 I believe this notation is used quite a lot in Structure and Interpretation of Classical Mechanics.
Mar 4, 2021 · Scheme prides itself on being an expression-oriented language, meaning, every expression returns its value. It so happens that the value of the define expression is not the value of the entity (here, function foo) it is defining, which might be a bit counter-intuitive. So either return foo after defining it, as shown in the first answer, or ...
