expr is a command line utility on Unix and Unix-like operating systems which evaluates an expression and outputs the corresponding value.
Used in a Sentence
expr
Definition, parts of speech, synonyms, and sentence examples for expr.
Editorial note
We can justify writing return (expr); using the same arguments that justify the sizeof (expr) convention.
Examples16
Definitions1
Parts of speech1
Quick take
expr is a command line utility on Unix and Unix-like operating systems which evaluates an expression and outputs the corresponding value.
Meaning at a glance
The clearest senses and uses of expr gathered in one view.
Definitions
Core meanings and parts of speech for expr.
N
expr is a command line utility on Unix and Unix-like operating systems which evaluates an expression and outputs the corresponding value.
Example sentences
We can justify writing return (expr); using the same arguments that justify the sizeof (expr) convention.
This time the expr coming out of the macro is a copy and so it has no source info.
Suppose we represented Add instead as: case class Add(exprs: NonEmptyList[Expr with NotAdd]) extends Expr case class Const(value: Int) extends Expr with NotAdd case class...
There's really no need to have either section on lexer or parser when working with s-expr.
The type of the first operation would like more like this: notAddOp: Contains NotAdd a -> Expr a -> T a...
Each statement prints a value, but it would be rare to see something like `expr' be a mnemonic for that value.
For example, fact 'init variables and return expr' { should let(a=1,b=2){a+b} => 3; } to what point will the let bindings be valid?
For many people reading and/or writing C-style is easier than s-expr (Lisp).
Did they preserve the s-expr structures in the C++ version?
If you grok expr(), you grok the whole thing.
This reminds me of another article which I'm pretty sure was posted on HN as well about a single bit being randomly flipped on someone's `expr` binary as it was loaded in memory.
Yes, in this situation owned Expr pointers are returned, and fortunately I know that Expr contained no borrowed data (with a lack of lifetime annotation that is easy, but in C++ you might have to check) But there could be other pointers being passed around internally (eg replacing the old pointer from a field of an argument with a new one, one which actually is short lived or is being iterated over.
Quote examples
"They also sometimes group expressions and disambiguate precedence" But it's obvious: "expr ( [expr,]* expr)" is a call - always.
In the C++ Working Paper, the Standardese is N4527 5.2.2 [expr.call]/4 "When a function is called, each parameter (8.3.5) shall be initialized (8.5, 12.8, 12.1) with its corresponding argument." followed by 8.5 [dcl.init] where /17.8 has a nice example: "Note: An expression of type "cv1 T" can initialize an object of type "cv2 T" independently of the cv-qualifiers cv1 and cv2.
-> Expr 'NotAdd You could also use True and False instead of Add and IsAdd, or even type-level string literals as arbitrary symbols: data Expr:: Symbol -> * where Add:: [Expr "NotAdd"] -> Expr "IsAdd" Const:: Integer -> Expr "NotAdd"
Proper noun examples
I tend to end up writing `Expr` objects directly when I'm building larger macros as I find them much easier to reason about.
Frequently asked questions
Short answers drawn from the clearest meanings and examples for this word.
How do you use expr in a sentence?
We can justify writing return (expr); using the same arguments that justify the sizeof (expr) convention.
What does expr mean?
expr is a command line utility on Unix and Unix-like operating systems which evaluates an expression and outputs the corresponding value.
What part of speech is expr?
expr is commonly used as N.