seq package:clash-prelude

The value of seq a b is bottom if a is bottom, and otherwise equal to b. In other words, it evaluates the first argument a to weak head normal form (WHNF). seq is usually introduced to improve performance by avoiding unneeded laziness. A note on evaluation order: the expression seq a b does not guarantee that a will be evaluated before b. The only guarantee given by seq is that the both a and b will be evaluated before seq returns a value. In particular, this means that b may be evaluated before a. If you need to guarantee a specific order of evaluation, you must use the function pseq from the "parallel" package.

Evaluate all elements of a vector to WHNF, returning the second argument

Evaluate all elements of a vector to WHNF, returning the second argument. Does not propagate XExceptions.

Evaluate each monadic action in the structure from left to right, and collect the results. For a version that ignores the results see sequence_.

Evaluate each action in the structure from left to right, and collect the results. For a version that ignores the results see sequenceA_.

Evaluate each monadic action in the structure from left to right, and ignore the results. For a version that doesn't ignore the results see sequence. As of base 4.8.0.0, sequence_ is just sequenceA_, specialized to Monad.

Sequential composition of two DataFlow circuits.

Like seqX, but will also catch ErrorCall exceptions which are thrown. This should be used with care.

seqErrorX (ErrorCall msg)  b = b
seqErrorX (XException msg) b = b
seqErrorX _|_              b = _|_

Like seq, however, whereas seq will always do:

seq  _|_              b = _|_

seqX will do:

seqX (XException msg) b = b
seqX _|_              b = _|_

deepseqX: fully evaluates the first argument, before returning the second. Does not propagate XExceptions.

Either seqX or deepseqX depending on the value of the cabal flag '-fsuper-strict'. If enabled, defaultSeqX will be deepseqX, otherwise seqX. Flag defaults to false and thus seqX.

Like seqX in simulation, but will force its first argument to be rendered in HDL. This is useful for components that need to be rendered in hardware, but otherwise have no meaning in simulation. An example of such a component would be an ILA: a component monitoring an internal signal of a design. The output of such a component (typically a unit) can be passed as the first argument to hwSeqX to ensure the ILA ends up in the generated HDL. NB: The result of hwSeqX must (indirectly) be used at the very top of a design. If it's not, Clash will remove it like it does for any other unused circuit parts. NB: Make sure the blackbox for the component with zero-width results uses RenderVoid