[Patch] Support implicit concatenation in list comprehensions
Using the -XImplicitConcatListComp option turns on implicit concatenation in list comprehensions. What this means is that you can write several things separated by commas in the "body" of a list comprehension, like so
[x, x | x <- [1..10], x `mod` 2 == 0]This program produces the following output
[2, 2, 4, 4, 6, 6, 8, 8]The effect is the same as if you had written
concat [[x, x] | x <- [1..10], x `mod` 2 == 0]but more concise, and more likely to be optimised well by the compiler.
NB: this was originally proposed in the SQL-like list comprehensions paper.
Trac metadata
| Trac field | Value |
|---|---|
| Version | 6.10.4 |
| Type | FeatureRequest |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | Compiler |
| Test case | |
| Differential revisions | |
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| CC | |
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